Uh... this seems a bit broken. Guy played Warsong Commander, followed by a free Molten Giant, so 8 damage, then Brewmastered the Giant, played it again for free, and was allowed to hit me again with it. To me, if they don't let you attack with a weapon you just equipped, it should be able to tell that the person already attacked with the Giant, and not let him do it again.
And yes, I realize it was probably a design decision to let people do that, but it just feel cheap. 16 free damage for free. More if he another brewmaster in his hand since he still had 5 mana left after doing that.