Like all Red XIII's weapons, Plus Barrette is not rendered or visible in-game, and cannot be thrown.
The Plus Barrette can first be found at Mt. Nibel. It is obtained near the bridge in the first area of the location.
As the Plus Barrette has a base Attack stat bonus of 39, the base damage for physical attacks when the Plus Barrette is equipped is in the following formula:
The Plus Barrette has modest stats, with a low Attack Boost close to the Silver Barrette, but a significantly higher Magic boost than the Magic Comb. Its double AP growth can be useful for grinding, and is Red XIII's best weapon for this.
The Magic Comb has four single Materia slots (meaning none may benefit from Support Materia). These slots should each be given to Materia that the player wishes to level up with the weapon. For Red XIII, this limitation can be detrimental, as he is best suited to spellcasting, and the lack of All Materia prevents several Magic Materia from clearing waves of enemies. Early on, it is best to bring along a character with the Enemy Skill Materia, to provide abilities such as Matra Magic or Aqualung to clear waves, though later Magic Materia allow Red XIII to cast spells that hit all.
The Plus Barrette outclasses Red XIII's Magic Comb in terms of stats and providing an additional slot. With the Plus Barrette, Red XIII is equally as competent at AP grinding as other characters with weapons that have four Materia slots at double AP growth.