sorry, but walkers havea weapon skill, meaning that you will hit normally, not on 6's like normal vehicles. i would go for a fist because berzerkers get an insane amount of attacks. where an SM champ would get 3 attacks on the charge, a skull champ gets 4, hitting on 3's against most normal infantry. the fist is highly beneficial for pulping ICs and big stuff, like monstrous creatures.