The chain saw sword. I mean it's a Chain saw...but as a sword. It even comes as an axe or a fist. That and the Bolter. It's simple design, yet deadly.
Main Rules Maces,Swords,Axes are Power weapons. Sword AP 3 ST - Mace AP 4 ST +2 Concussive Axe AP 2 ST +1 Unwieldy