The Jackhammer

The Jackhammer is a two-handed mace good for warriors, paladins, and shamans. It offers a haste proc (63.2@45), relatively high DPS and a nice looking model. With a Paladin's Seal of the Crusader it offers a 1.37 attack speed, nearly half. With a Shaman's Flurry and zerking, it has 1.102 speed.

Source
This item is a rare drop from Trash Mobs in Uldaman.