A Wergild is a debt paid to a family for damaged property or a deceased member by those deemed responsible as restitution for the death or damage. The family who suffered the loss of life or destruction of property can chose how the wergild is paid off.
Magnus Chase and the Gods of Asgard
The Hammer of Thor
After returning home, Hearthstone is told by Alderman that he must finish paying off Andiron's wergild, covering the Brunnmigi’s pelt with gold, before he is given the Skofnung Stone. After getting the treasure from Andvari, they cover the pelt and Anderman declares the wergild paid.