Standard TroopersThe typical trooper has skill 12 with his blaster carbine, which has an accuracy of 10. Assuming the soldier braces (+1) and aims (+10), he has a skill of 23, which means that he's got a pretty good accuracy out to ~70 yards. If he's mobile and on the move, that accuracy drops substantially to making effectively wild shots. Troopers come equipped with plasma grenades, which will kill even another trooper in the same hex, and kill or seriously injure unarmored combatants out to 1 to 2 yards from the explosion point. The typical trooper also sports 60 DR on the chest and 30 DR elsewhere, making him an exceedingly tough nut to crack. Their armor grants them microclimate control, is sealed against environmental hazards, and grants them IR vision, making them excellent night-combatants.
A typical trooper will probably crouch behind cover and lay down some massed fire with his squad-mates. A careful trooper will aim, and an aimed shot will hit. If they need to advance, they'll cover one another with supporting fire while making use of cover, but it none is available, they'll advance in the open and trust in their armor. If their opponents use cover, they'll use grenades to flush them out into their arc of fire.
Troopers have three "supporting" types: The assault trooper, the heavy trooper, and the recon trooper.
The assault trooper sports heavier armor and superior close-combat weaponry. In an open-conflict, an assault trooper likely carries shock grenades and/or a flamer. He'll lead assaults on enemy positions, with his superior armor absorbing enemy fire, and his superior training allowing him to spearhead the attack. Open conflicts aren't really his bailiwick, however. He's better at urban conflict or ship-boarding operations.
The heavy troop is generally equipped with a missile launcher or a gatling blaster. In the former case, he'll tackle hardened targets, such as entrenched "machine gun nests" or tanks, and in the latter case, he'll offer supporting fire to his side, either to defeat assaults, or to keep the enemies heads down while his allies advance. The heavy trooper is ideal in open conflict, but suffers some in urban or ship-board conflict.
The recon trooper has superior infiltration skills and a powerful sniper rifle. He'll slip past enemy lines and find out what the enemy is up to. He might engage in sentry-removal with his vibro-knife, and in open conflict, he'll focus his sniping efforts either on removing high-priority targets (officers) or on frightening to soldiers into keeping their heads low while the standard troopers and assault troopers advance on the enemy position.
In truly open conflicts, soldiers will bring combat vehicles, like hover-tanks. A hover tank features 1000 DR on its front and turret and 500 elsewhere. One needs something like a missile to remove it from play, and preferably from the side, rather than the front.
Soldiers aren't always constantly prepared for battle. They could be on the move, in which case they likely use combat vehicles like Military Vertols or Hover IFVs to get around or, more rarely, they'll march. In such case, fighter support and recon troopers will scout out the terrain to prepare for any ambushes. Alternatively, they could have settled in for the night, in which case they've set up some temporary defenses like razor wire or x-ray fences, some surveillance cameras and regular patrols, usually in the form of standard troopers and a few well-placed recon troopers.
Force Sword Tactics
A force-swordsman, with nothing but a force sword and the Force Sword skill, is just so much meat for a military force. He lacks the range necessary to deal with the troopers: if he charges, they'll cut him down before he's within 50 yards of them. If he huddles down behind cover and waits, then plasma and shock grenades will drive him out of cover in time to be cut down by blaster fire.
A force-swordsman needs cinematic skills and psionic abilities to deal with the problem. First, he needs mobility, which is provided by super-jump and flying leap. If he can swiftly cover the ground between himself and the enemy force and engage them in close combat, suddenly the dynamic changes. A force sword is more then capable of cutting through even the heaviest combat suit. An assault trooper with a neurolash baton might be able to fend him off, but in practice, everyone in melee with the force-swordsman is likely going to die. But the golden standard for that mobility is roughly 70 yards in a turn, which is a tall order, or the throwing range of a grenade: the forceswordsman can take cover, wait for the assault team to approach him, and then counter-ambush them with a flying leap that brings him into contact with them, and then retreat back to cover before he can be cut down by weapon fire.
Using the chambara rules allows a weapon master or a trained master to make a full jump without concentrating. I seem to remember a rule about maximum jumping speed rule, but for the life of me I cannot find it. Still, using GURPS Calculator, we can see that a Move 6 character with Super-Jump 3 can cover 24 yards in a single jump. With Flying Leap, that triples to 75 yards, and he'll cover half of it in a single turn, meaning that Super-Jump 3 and Flying Leap allows a character to cover the entire distance between himself and the typical effective range of troops in open battle, and he'll only be exposed, mid-air, for a single turn. When he hits, he'll be able to make an attack that does triple damage too.
Precognitive parry helps him deal with that return fire and extends the range of his movement, because it gives him a way of dealing with blaster fire. Precognitive parry isn't easy, but if he has it, he can afford to approach in the open. Precognitive Parry requires Danger Sense, which means that a character with Precognitive Parry has little to fear from a Recon trooper. The only problem with this tactic is the sheer massed fire. Each additional parry is at -2 for a weapon master, or -1 for a fencing weapon or a force sword in defensive grip. This also makes the Heavy trooper a grave threat, as he can lay down a withering hail of fire with his gatling blaster, or he can hit the space knight with an area attack like an explosive missile. For that matter, all soldiers carry grenades, thus defeating a standing space knight is just a matter of tossing some grenades his way.
But if a space knight combines both high mobility and extreme defense, he might well get through that firepower. He minimizes the amount of time he has to deal with the massed fire, and he can readily avoid being pinned down by grenades and missiles (grenades take time). Using acrobatic tumbles will both give him a bonus to dodge attacks, and it will force his opponents to apply his speed as a penalty to their attack, which reduces the number of hits that get through. Rapid movement also makes aiming impractical.
Incidentally, a weapon master deals 8d+16(5) burn damage with his force sword. A tripled power-blow deals 24d+48(5) burn damage, which penetrates an average of 660 DR, which means a sufficiently epic space knight can kill a tank. However, he has little recourse against flying vehicles without considerable levels of super jump and flying leap.
Conclusion: A force sword is an effective weapon on an open-battlefield, provided its wielder is sufficiently superhuman.
Force Sword-and-Buckler Tactics
A force sword-and-buckler combatant, with nothing else, isn't so bad off. The shield can only block once per turn, but it can block blaster fire (or, at least, it can benefit his dodge sufficiently that he can survive fire). With sufficient defense, he can afford to march his way towards the enemy, though a full 70-yard death march is impractical. Still, one could imagine a legion of well-armored, shielded soldiers marching down on an infantry column. Removing the need for high mobility means that the force sword-and-buckler combatant can wear heavier armor, further protecting him from attack.
Snipers pose more of a problem for this sort of combatant because he can lie in wait until the force sword-and-buckler combatant is exposed and then take him down. The cinematic combatant can use Precognitive Block, which means he must have Danger Sense, which protects him against sniper fire. Explosives pose less of a risk to the combatant, as he can reasonably claim his shield as cover.
Once engaged in battle, the force sword-and-buckler combatant is every bit as lethal as the force-swordsman, able to cut a combat-hardsuit-wearing trooper in twain. The ability to march on one's enemy while behind the cover of his shield and heavy armor and then dominate the battle once melee range is reached means he has a huge advantage. We could even replace the force sword with a force glaive, though this sacrifices some advantage against other force-swordsman.
Conclusion: Even without cinematic abilities, a force sword and buckler are an effective combination on the battlefield.
Characters wielding blaster carbines, grenades and armor of their own can engage in precisely the same tactics that troopers use right back at them. Such tactics were designed for defeating a military force, so I trust it would be very effective. Sniper rifles, blaster carbines, gatling blasters and missile launchers are all highly effective ways to deal with enemy soldiers.
Gunslingers face several problems when dealing with a fully militarized force. First, standard trooper armor will completely defeat standard blaster pistols and has a fair chance of completely stopping a heavy blaster pistol. Second, blaster pistols are considerably less accurate than carbines, which means that they'll have a hard time dealing with the ranges involved. A character with a pistol is better off waiting until his enemy gets close and then taking advantage of his superior maneuverability (lower bulk) to put them down, but even then, their armor will likely stop most of his attacks.
A gunslinger can take advantage of many of the same tricks a force-swordsman can, but he lacks most of the advantages of a force sword. The pistol deals less damage, penetrates armor less well, and cannot parry blaster fire. He's stuck with dodge as his only real form of defense, though gunslingers have less problems firing on the move than force-swordsman have when attacking on the move, and once he gets close, he's still forced to deal with his inferior armor penetration. The best way to deal with that is sufficiently superior skill that the character can afford to make targeted attacks.
Conclusion: A pistol can be effective against armored troopers, but it's not an ideal tactic.
Other Melee Weapons and Unarmed Combat
No melee weapons approaches the force sword for lethality, though the Neurolash is a fairly effective weapon for dealing with armor. The heavy armor of the troopers will defeat weapons like vibroknives and fists. Wrestling and Judo techniques will have an advantage against heavily armored troops, but you still have to get close to the enemy to do that, and you lack the precognitive blocks and parries of a force-swordsman, and Judo suffers if you wear armor. In short, take the worst of force-swordsmanship and combine it with the worst of pistols, and you've got unarmed combat on an open battlefield.
Conclusion: Don't bring a knife (or a fist) to a gun fight
Defeating Troopers by Stealthy Means
A force sword is not an optimal stealth weapon. In one sense, it excels in that the character can bring it close to the enemy without alerting them to its presence (as it's exceptionally small), but for silent sentry removal or killing soldiers in their bed, a brightly glowing and loudly humming weapon is less than ideal.
The preferred tactic for a stealthy force-swordsman might be to slip past patrols, bring himself right up to a high priority target, then activate his force sword (noting that it takes a full second for the force sword to full materialize) and then lay waste to everything around him. He'll still have to get out, but a force swordsman is less an assassin than an ambusher (possibly a suicidal one).
Force Sword and Buckler
A glowing shield is even less stealthy than a glowing sword. The same tactics with a force sword is necessary, though putting yourself in a central spot means you'll be attacked from all sides, which removes much of the advantages of a shield. Not ideal.
Military tactics are generally even less ideal than a force sword. A blaster carbine makes a lot of noise and large flashes of light when it fires, to say nothing of missiles and gatling blasters... but a military combatant would need to use different tools, namely explosives and sniper weaponry. The ideal military ambush involves planting explosives either on the trail the enemy will take, or near the fortifications of the enemy, then takes up a sniper position. He fires off the explosives at the right time, and in the confusion, begins to pick off the enemy from a distance, and then melts away before they can find him and eliminate him.
The same problems facing a force-swordsman faces a gunslinger. Once the blaster is fired, most enemy will be alerted and, once against, the pistol lacks the defensiveness and sheer destructive capabilities of a force sword. The ideal pistol stealth-tactics likely involves a quick ambush followed by a rapid retreat that takes advantage of the pistol's superior mobility. The pistoleer should think of is attack as more of an ambush than an assassination.
Other Melee Weapons and Unarmed Combat
Here, knives and fists shine, as neither makes much noise or loud flashes (though a vibro-knife has an audible hum). Sentry removal techniques become difficulty if the enemy wears 30 to 60 DR, as even a vibro-knife (which deals 2d(3) cutting) will be unable to penetrate that much armor. However, a telegraphic (+4) all-out (+2 damage) attack to chinks in the armor with a vibro-knife will reduce the DR to 5, and then a stab (1d+2) for the vitals or the throat might be sufficient to at least stun the target for a second attack. Unarmored targets (sleeping targets, for example) can be easily dealt with via a knife in the dark. Note that while a nuerolash baton will definitely get past armor this way, it causes agony, which means a shouting, screaming soldier, who will alert everyone around you.
Unarmed skills are less useful except to control the fight, because you'll be unable to land a choke hold over all that armor, and your strikes will be similarly useless.
As effective as unarmed combat and knives could be in stealth combat, it might be worth examining them again in detail and looking for ultra-tech melee options that might help them deal with the heavier armor of trooper in the right circumstances.