The "Mace of Death" was put in by the development team, but eventually removed. To get it back, download the update for the game and go to an expansion-only area. Save, then exit the game. Delete the expansion and load your game. You will be in a bizarre version of Bruma with a random troll in a building. There will also be a "Mace of Death" on the ground or in a chest. It does at least 4,000 damage. Pick it up, save the game, and re-download the expansion. You now have the most powerful weapon in the game.