He pauses for a moment, uncertain. His training was generally on live (for the moment) targets--this is kind of weird. Then he gives a little shrug and lashes out at the punching bag a few times.

It's not a completely inept series of blows--his fingers are in the right place and there's a swift, clean force behind the motions. But he's still moving his body and limbs as if he were wielding a weapon. Even when he does try to disable rather than kill (which is usually a prelude to killing anyway), he does it with a blade in hand.