Ghal Maraz ('skull-splitter' in the original Khazalid) is the name of Sigmar's legendary warhammer. The mighty weapon was gifted to the young Unberogi prince in IC -15, when Sigmar rescued the Dwarf High King Kurgan Ironbeard from captivity in a greenskin warcamp. In addition to its practical use, the warhammer was also a symbol for the treaty of friendship between the Dwarfs and the Unberogi that lead to the spread of ironsmithing, literacy, and engineering among the tribes of man.
Ghal Maraz is one of the greatest weapons ever made, rivaling even the great Ancestor Weapons of old. It has even been suggested that the weapon possesses some form of sentience, favoring some users over others. What is known is that the weapon has never failed its wielder in battle.
When Sigmar vacated the Imperial Throne in IC 50, it is unclear whether he left his warhammer upon the throne along with his crown, or whether he took it with him. Historical texts differ on this point: some say that the Emperor left the warhammer on the throne, others that he took it with him, and still others that the Dwarfs returned it to a future Emperor some years later, saying that Sigmar had left it with them on his journey to the east. Despite the historical controversy, both the Cult of Sigmar and the Emperor insist that the mighty warhammer in the possession of Karl Franz is the original.