I'm not sure what build you're using, but it seems hammers are bugged currently and only hit once. You can test easily against something big - hammer hits enemy and does damage, swirls round and hits enemy again but does no damage. Perhaps it's intentional, but either way ye olde hammerdin isn't great atm.
I've not started a Crusader yet, but I've got a few bits and pieces of leveling gear stashed and ready. I'm still having fun in adventure mode trying to get my Wizard back to where she was pre-RoS - farming T3 with ease.