The Skofnung was a powerful magical sword, earlier owned by prince Gellir. Later, the sword got destroyed in the process of freeing Loki.
The sword was forged by King Hrolf and contained the souls of his twelve berserker followers. A man named Eid stole the sword from Hrolf. Eid, in turn, lent it to a prince, Thorkel, who never returned it. When Thorkel died in a shipwreck in Iceland his son Gellir found the sword and used it in many battles. When Gellir died in battle the sword was buried with him.
Hundreds of years later, Loki planned to used the sword to free himself. He did so by convincing Randolph Chase to cut him free using the sword. At the end of the book, Randolph used the sword and its matching stone in Loki's cavern to cut Loki's bonds and free him.
However, the sword was drawn in the presence of women such as Samirah, Alex, Thrynga and Sigyn. This was against the rules of using the sword. Hence, the berserker souls in the sword grew angry. With a high-pitched shriek, they began to attack Randolph. As Randolph freed Loki's bonds, the sword dissolved and with it, Randolph's body dissolved too.
- The sword cannot be drawn in the presence of women (as long as they are concious).
- The sword cannot be drawn in direct daylight.
- The sword can only be sheathed after it has tasted blood.
- The sword can only be wielded by those of noble lineage.
- The Skofnung Stone can be used to sharpen the blade.
- According to Jack, the sword is a female.
- The kenning of the Skofnung Sword is Blood River.