Im not ASSUMING Revan killed Mandalore the Ultimate, I am STATING it. It has been oficially said that he did. And yes, it was hand to hand:
Revan battled and killed Mandalore the Ultimate himself. I think that says that Revan, wielding a lightsaber that was ineffective against the armor which Mandalore was wearing, and battling a non force sensitive with the force isnt technically battling, it means 1 thing: hand to hand combat.