Devorak: stop generalizing so much..sponge bob! if you were listening, which you weren't Ensemble studios did say that this story takes place before the original halo. So who the hell says that it's a one hit kill way back when.
Think outside and not in it. Better try thinking at all and you'll get the just of it.
youre right, i admit im generalizing, but because the swords is one of the oldest covie weapons, as seen in the h2 dvd (the age of confilc part) my guess is that hey would have had enough time to perfect it, Compare it to how humans use metal: technology these days allow us to create alloys that can withstand intense heats of jet fighter's reactors, armor that can resist a tanks firepower and we can sharpen them enough to mae planes easily break the sound barrier. we can even create diamonds, that are harder and can be sharpened much more than any metal.
If some crazy rich man did a sword with the latest technology, it would be capable to cut a person like warm butter. and covies have had enough time to play with plasma, most probably even a hundred years ago, it would have killed in one slash
**edit: also do you even know what plasma is? our sun (plasma too) burns at 5 million degrees Kelvin. i dont know how much that is in farenheit, but trust me, a plasma sword touches your body, most probably you will die. it is too much for any stuff to withstand it. its not like you sharpen it.
