Haha, I just posted the same question about two weapons. Yes, a mouse can wield two weapons at once, say a sword and shield or sword and dagger. But, he must choose which weapon he is using for the following actions. He has to use the selected weapon until he choose actions again, at which point he can change to a different weapon. See page 119.
As for a mace, I’d give it Slow -1D to defend or Feint and Bashing +1D to Attack.
When we made characters for MG last sunday, one of my players wanted a Morning Star and I made him use the stats for Axe. Both are high impact weapons although the Axe is cutting as well. That’s the same stats as Jason’s.