I've since sold the item in question, but I do have a level 8 one handed sword that deals 20-21 damage; I specifically picked it up because it has higher damage than another level 8 sword that I saw.
I imagine this is the same situation, with this sword just being a better sword.
That said, it really is disappointing that it's a difference of 4.5% damage. With dual wielding getting 10% chance to dodge from that one talent, and more damage from certain buffs, it's hard to justify using a two hander.
