The Angel's Feather is an item first seen in the first Kid Icarus game. In the first two games, it grants Pit flight and can be used to recover from falling. In Kid Icarus: Uprising, Feathers are used to unlock panels on the Treasure Hunts.
Merchants sell this for 390 Hearts, unless Pit's bargained them down, in which case he'll get a mighty discount to 150; failure, though, raises the price to 630. A Black Marketeer sells Feathers for 450. It can be bought at shops or found in Treasure Chambers. It is activated automatically (and consumed) when Pit hits the bottom of the screen, allowing him to fly for a short amount of time in an attempt to recover his footing. A near-necessity in Skyworld, but also useful in the Overworld when attempting to traverse the large seas. Once Pit has equipped the Wings of Pegasus (one of the Three Sacred Treasures), Angel's Feathers become useless and can never be used again.
Kid Icarus: Of Myths and Monsters
This item is only found while traveling and will not be found in any shops. It grants Pit the temporary ability of full flight, but only lasts for several seconds, much like a primitive version of the Power of Flight. Because this game allows Pit to back-track to areas he's already been to at the lower parts of a stage, it is not as important as it was last time, but it is still useful for accessing hard-to-reach areas and avoiding obstacles.
Super Smash Bros. Brawl
The "Wings of Icarus", is Pit's up special move. It appears to be a combination of the Angel's Feather and the Wings of Pegasus as they have a similar appearance as the Wings of Pegasus, but they function like the Angel's Feather. This move allows him to fly upwards, the wings turn blue, and then after a moderate period of time Pit becomes helpless. It is considered one of the best recovery abilities, mirroring its importance in the first Kid Icarus. However, unlike any other fighter in the game, if Pit is hit with any attack while flying, he cannot use the "Wings of Icarus" until he lands on the ground again.
Kid Icarus: Uprising
Although not an item used in battle, the Angel's Feather, referred to simply as Feather, is found and used in the Treasure Hunt panels. They are unlocked through certain panels and can be used to unlock other more difficult ones. Each Treasure Hunt contains five feathers in all.
After the game's credits, a white feather on the ground is found shining in a white spotlight. If the player waits for five minutes on the screen, Hades's voice appears signifying his soul was not entirely eradicated.