Frostslayer was forged in Nidavellar, the land of the dwarves by the same dwarves who forged Thor's hammer. Frostslayer was given to Grundi Olafson on his fifteenth birthday by his father, Olaf Ottarson. When it was given to him, it had not been named Frostslayer yet, it was a nameless sword. But when Grundi killed a frost giant in combat with the sword, it was given a name. Ancient Asgardian writing was engraved on it which could only be seen at moonlight. The writing said "Frostslayer" because it had slain a frost giant.