Oathkeeper is one of two Valyrian steel longswords made from Ice, the greatsword of House Stark, under orders of Lord Tywin Lannister. While initially given to Jaime Lannister by Lord Tywin with the intention of making it an heirloom of their house, Jaime instead gave it to Brienne of Tarth for the task of rescuing Sansa Stark. Its sister blade is Widow's Wail.