Ok, founds these stats done by some random person online.
So don't know how reliable they are...
melee_weapon easy/normal/advanced/expert/versus
fireaxe 0/2/2/7/2
crowbar 0/1/1/5/1 (no ff on first hit)
tonfa 0/1/1/5/1 (random hits make no ff)
electric guitar 0/2/2/7/2
frying pan 0/2/2/7/2
machete 0/1/1/5/1
katana 0/2/2/7/2
cricket bat 0/1/1/5/1
chainsaw 0/1/1/5/1
baseball bat 0/2/2/7/2
And this only accounts for damage - not range or speed (or gibbing ability)
+ I have no idea what exactly those numbers mean...
And I think these are only FF damage.