Oathkeeper is a sword made from the greatsword of House Stark, Ice. It got reforged by Tobho Mott. After the Starks got massacred, Ser Ilyn Payne took Lord Eddard Stark's sword. He held on to it until Lord Tywin Lannister returned. When Tywin learned that Stannis had Lightbringer, he collected Ice from Ilyn and gave Tobho to create a sword after House Lannister's image. From Ice, Tobho made two swords; one became Otahkeeper and the other Widow's Wail.