When you board a ship there are several things that are almost always true: 1. You've already beat the shit out of the ship
2. Seeing as you've beat the shit out of the ship, the engines, sensors, and (most importantly) whatever is used as artificial gravity is not working well.
This last bit ensures no slug throwers are going to be present (thanks to the recoil). Also, seeing as the boarder needs to take control of the situation, it is very advantagious to creat a vaccuum when attacking (the boarding troops will definately be in vacc suits, some or most of the defenders might not be, and thus giving the zero gravity trainer boarders a hefty advantage. Vibro-blades that are able to open large gashes in vacc suits with little to no effort would be very useful. One might mention lasers at this point, but seeing as we're all being very technical now, lasers are easily made useless. Flexible reflector suits (like the vests that bike riders use) would make you invunerable to lasers. Contrary to the reflec armor stats in the rule book, the fact is lasers dont harm any reflectable matierial at all, and a reflective suit would be easy to make, flexible, and could cover your eyes (reflective on one side, see-through on the other).