Nah, I like Garret's head-knocker from Glen Cook's series. Drill the core out, fill it with lead. You're really whacking them with what amounts to a lead pipe covered in wood.
Oh, which brings up nastier ideas. Mistborn powers involve burning or ingesting metals (unclear on specifics)? What keeps people from having walking staves, jewelry, breastplates, rings, etc. made from the useful metals? You'd start missions out looking like Mr. T and end up looking like a walking bruise with one or two metal trinkets left.
Or should I just shut up until I read the novels?