The Sheriff Star is one of the rarest accessories in the Wild Arms series of games. Only the Full Libra, with its all-status negation effect, can really make any attempt to claim the the title from the Sherrif Star of the best accessory in the game.
The Sheriff Star has been in every game. There is usually only one Sheriff Star in the game, and it is the prize for defeating the powerful Superboss Ragu O Ragula. It is possible to create Sheriff Stars in Wild Arms 5, however. Sheriff Stars also get the occasional honor of being retained in a file when a New Game+ is started.