Rocksmasher is a bow used by Grundi Olafson. It is called Rocksmasher because it a single arrow from it can smash a rock to pieces. It was forged by the dwarves in the land of Nidavellar, who also forged Frostslayer and also forged Thor's hammer Mjolnir. The bow is made from the hardest steel crafted in Dwarven mines and wood from Yggdrasil the world tree in Norse mythology.
Rocksmasher was given to Grundi Olafson along with his sword Frostslayer, on his fifteenth birthday. He immediately named it Rocksmasher after destroying a boulder with a single arrow.