Black acquired this mace from the Paladin Deathknight in episode 17. Draven later enlarged it with knowledge gained from one of the Ytaran artificing tomes he found in Ginaron.
The head is shaped like the classic Sirius rook symbol and the handle has a Claw of Bahamut symbol on the base. This lends weight to the theory that the platinum dragon deity and the god of protection are one and the same.