Dave, Fist of Odin
If the Spirit Hammer does the same damage as a mace, that's a d6+1 base, so doubled gives 12 points. But I don't remember if a hammer does a d6+1, or a d8, or a d4+2, so it might be different. If only there was some sort of ancient tome we could consult.
Also, am I done for the round when I'm hammering, or can I do other stuff? Some of the other stuff I might want to do are pulling Cinder out of the fray, and giving him a healing potion.