shovel would be my bet
I read about this guy who tried to kill someone he knew. He figured one good clobber with a bat would do the job...well, turns out he had to smack his victim repeatedly--if memory serves, some 6 - 8 times before the guy would stop getting up.
And there's something about a shovel that just seems...I dunno...Hitchcockian. A bat is so round...a shovel, so blade-like.
The thought of it's creeping me out...