Three Sacred Treasures
The Three Sacred Treasures are legendary items once possessed by Palutena, ruler of Angel Land. In each game, they reside in Sacred Caskets that only appear after defeating each Gatekeeper in a Fortress. Invariably, the treasures cannot be used until the final stage in each game.
Appearances
Kid Icarus
When Medusa took over Angel Land, the three Treasures were stolen from Palutena's army and placed into the clutches of the Fortress Gatekeepers. Pit needs the power from these artifacts to defeat Medusa, and thus invades the gloomy labyrinths to reclaim them.
Kid Icarus: Of Myths and Monsters
To avoid the Treasures falling into the wrong hands, Palutena stashed them in the Fortresses. However, since Pit's quest is to gain the strength to use the Treasures, these challenges only serve to increase his strength and make him worthy enough to use all of them by the time he reaches the Palace in the Sky.
Here the Mirror Shield was replaced by the Silver Armor.
Kid Icarus: Uprising
The Three Sacred Treasures were confirmed by a translation to be in the game, and are said to be in the possession of the Star Pirates.