Oh, shut up and help me remodel the Balthier (World of Final Fantasy) page!
Balthier does not make an appearance in the game's main storyline, but is available as a summonable Champion as free downloadable content with the update patch to version 1.03. In the Maxima version, Balthier is already included (along with Sephiroth).
An image of Balthier appears in the Who's Who, but does not have a written entry for him.
An arrangement of "The Fates" from Final Fantasy XII plays when using Balthier's Champion Medal. The player may select this theme as the background music for battles from the Config section of the main menu, labeled as "Champion Theme: Balthier".