Jop, if you think about the insane number of undeads you'll find in the game, and that not all the enemies are undead, keep both weapons
You can exchange them at the beggining of every round - of course, the sistem is a bit clumsy but hey, nothing is perfect. I have a fighter using only two handed weapons - it happens that one of the weapons - a spear, a longsword and a hammer - is the same you have there the hammer against undead.
But look if that dont make your character be delayed in combat because of incumbrance. Otherwise keep them with one weapon to destroy undead and other to normal foes.