I’ve played a fair bit of L4D2 and one of the actions which can be performed by a player is to physically strike or shove with the currently held weapon.
So a shotgun, for example, is held with both hands, one hand at each end, and used as a stave to shove anything near away from the player.
This I think an excellent mechanic - it seems extraordinarily natural in emergency to hit or strike with whatever you have in your hand, rather than having to switch to the crowbar (which is too slow for instinct - it can only be conscious). I found myself instinctively trying to push headcrabs away when they jumped close.
I think also, very importantly, this brings the player more into the game - more into the game-world, by being able to more instinctively interact with the game world and the creatures within it.