Oathkeeper

The Oathkeeper is gained by speaking to Kairi in the Secret Waterway in Traverse Town, after her rescue in Kingdom Hearts. It has a decent reach and is well-balanced. It's a good substitute for the Lionheart, in case the player hasn't been able, or didn't want, to defeat Cloud and Leon in the Hades Cup. The Oathkeeper reappears in Kingdom Hearts II. The Oathkeeper is one of the two Keyblades Roxas uses, the other being the Oblivion. Roxas' Oathkeeper, however, is silver in color, unlike Sora's which is white. The Keychain motif is of Kairi's good luck charm; a Paopu fruit-like star for Sora, made of thalassa-shells, and Naminé's charm that was made of false memories for Roxas. Its shaft displays two hearts, and its handle bears two angel wings, contrasting the bat wings that comprise Oblivion's handle. The teeth are fashioned in the shape of the Kanji for "light" (光), corresponding to the Oblivion's Kanji for "darkness". It can be seen as a Keyblade of light, to balance out Oblivion's darkness.

In Kingdom Hearts: Chain of Memories, the Oathkeeper card is obtained after completing Destiny Islands on the 12th floor.

Since Oathkeeper's Keychain is Kairi's good luck charm, it could be suggested that Sora will no longer wield Oathkeeper after the events of Kingdom Hearts II, as Sora gave it back to Kairi.