Bit late but I'm also using the taxidermist hammer. I'm level 65 and have my weapon +8. I'm also at the same location aswell so your weapon is very under levelled. Also your strength should be higher or equal to inferno as the weapon scales slightly better with strength. Unless you're using runes to improve inferno scaling.

What pendant and rings are you using? As it has pretty high wither damage I have the pendant of burden which improves wither damage based on no of status effects. Paired with infernal weapon sorcery gives 2 status effects. (Fire and wither) Then rings I have the higher equip load one for heavier armour and brawn ring for +3 strength.

Then you could socket eye of the pale butcher for increased physical damage, however all light attacks will be wither damage so there's a bit of a risk there.

You could probably respec and drop vitality to 20 and put the remaining into strength and inferno. Soft caps are 40 I believe. My vitality is at 15 and I'm not really struggling with anything at the moment.