The Skull Hammer is an item from the Wind Waker found after defeating Phantom Ganon in the Forsaken Fortress. It is a huge warhammer with the head being built inside a large skull, with a small rock hammer shaped counterweight at the other end of the shaft. In the game it's used as a slow but heavy hitting weapon against certain enemies, and for hammering pegs into the ground to solve puzzles.
This model is quite hard. It isn't very big but has a lot of detail, especially around the jagged 'teeth' of the skull.