1: The melee weapons vibrate to do more damage and be more effective then a simple sword.
2: They are covered in a sort of substance that is one of the few things light sabers can't cut through.
3: I remember is KOTOR 2 that Attom Rand told you that in a fight between a fight between a guy with a sword and a guy with a blaster the guy with the sword will win as long as they can get close enough.
Essentially they are to be used just in case they encounter a Jedi, Sith, or a lunatic that got hold of a lightsaber.
