Station Self Defense Seminar
So we know how to damage a craft properly, but what can the guys inside do to defend?
Fresh from the Kerbal Space Program Field Study Institute I can offer some strategies for improvised space travel and short range transiting, containing something called the "most fuel efficient way to transit a kerbal from one craft to another". If done correctly, it can be used for self defense purposes against people in spacesuits going amok.
Usually includes a rope, good aim and lots of good luck: when attached to the station with some kind of rope (I think they have a specific name, but I can't recall) that should prevent EVAs from floating away, you can use this to apply force to whoever is at the other end of that rope. The centrifugal force will force the aggressor away as long as he is fixed. All you need to do is start spinning your station fast enough. Usually no EVA-suit has the thrust to nullify the forces applied this way. If you have some kind of rotation wheels (which is something I think is exclusive to ksp) you don't need to waste fuel on this, just electric charge.
As bonus, if you cut the rope in the very best moment you can send your aggressor in a predefined direction (like in front of the exhaust port of something that is about to accelerate). Or — more peacefully — this can be used to send EVAs at high speeds into a higher or lower orbit where they may rendezvous with another craft or station.
Of course, this may cause havoc inside your station if you have your staff and stuff floating around freely.
space ping pong
Works pretty similarly, but without the rope. You need a huge flat structure and the ability to rotate your station quickly enough. Big constructions might lack this ability, but smaller ones do excel with that.
Just wait until the aggressor is in front of said structure (solar panels might work, but usually are too fragile) and start spinning, slinging the aggressor away. It’s hard to aim with that technique (trust us, we tried), but you can easily push away stuff that starts to getting dangerous.
Sadly the aggressor might damage the surface used to do this, so use with caution.
Until now the aggressor usually could maintain the ability to fly back if his EVA suit did contain some sort of propellant in high quantities. So what to do with troublemakers that keep coming back?
Well, if your station owns a robotic manipulation device (well, some shafts with a clamp at the away end) you can try to grab the aggressor. What is done next is up to you. Hold him? Throw him away? Smack him into something else? bbq him in front of your main thruster? Well, use your imagination. If you are having your evil day you can try to squeeze his EAV so it will break and let the air out, but that’s way too cruelsome.
emergency heat shield
If your station owns some kind of emergeny-capsule, maybe you can just start this thing when the aggressor is right behind it. Its mass will be too much to counter with his EVA's monopropellant, and with a bit of luck he will getting stucked at it somehow.
Anyway, you will get him away, and in some cases he will stay there until the capsule enters the atmosphere again. Than he isn't of any problem for you any more.
Big fragile structures disqualify themselves for that tactic, but if you do have a big maneuver thruster you can just kick start your engine and fly away. Bets are that your ∆v is way bigger than his!
Just don't forget to stabilize your orbit once out of reach, or you will either do a surprise reentry or find yourself on a escape trajectory from your home planet.
So maybe your EVA does have a remote control that cannot be switched off... well, do we need to say more?
At the other side, most space suits own a communicator that is either impossible to turn off or at least pretty hard. So threaten the aggressor start singing the Russian national anthem (just applies if not a Russian patriot) or a freely choosen Justin Bieber song will make him reconsider. You could ask ground control to force 10 hours of nyan cat into his channel.
Sadly this may backfire, so take good care.