Pick up the plate armor, he'll barely score any damage on you. It looks like `[` and is in the dungeon somewhere (in addition to chain mail, which looks like `[` as well).
I had the plate armor and I suspect there was a bug with the axe (or perhaps a feature where one of the weapons does nothing), he didn't do much damage to me but I just had 100% miss rate. Second playthrough used the sword and dispatched him easily.
thanks!
funnily had it both times and got killed with good health.
anyway now it worked.