The Secret Book (秘伝の書 Hiden no sho) is a Stat booster that recurs across the Fire Emblem Series. When used, the Secret Book permanently raises its user's Skill by a set number of points that varies from game to game.
In Genealogy of the Holy War, the Secret Book is substituted by the Skill Ring (スキルリング Sukiru ringu), an item that must be placed in the inventory of any unit in order for its Skill-boosting property to take effect. The Secret Book is similarly substituted by the Skill Ring in Thracia 776, although this particular incarnation of the ring functions as an expendable item that permanently boosts its user's Skill by 2 when used.
InTearRing Saga: Utna Heroes Saga, the Secret Book's equivalent is a potion that is simply known as the Skill Plus (SKL プラス SKL Purasu), permanently raising its user's Skill by 2 when used.
• M25 - Hidden in the sand.
• Arial Mountains South - Random from Chest.
• Arial Mountains North - Random from Chest.
• Tower of Morse Floor 3 - Random from Chest.
• Tower of Morse Floor 5 - Random from Chest.