One of the Feathers
The Feathers are magical feathers that are in actuallity pieces of Sakura's Soul that were scattered across dimensions in episode one of the anime, and chapter one of the manga. Without the Feathers, Sakura will die.
Powers
Each Feather has great magical power, however it would seem that each has a uniqe effect on the surrounding area. For example, one feather has the power to grant a great increase in size and power to Kudons, while another can bring a virtual world into reality, while yet turns drawings into an alternate "world" (different from regular worlds because they don't exist in another dimension).
Feathers List
Feather 1:
Location: Hanshin Republic
Achieved: This Feather was given to Fai by Fei Wong before the start of the story. Fai made it seem as though it was stuck to Syaoran's clothes.
Feather 2:
Location: Hanshin Republic
Achieved: It's inside Masayoshi's kudan. Syaoran eventually defeats it and grabs it.
Feather 3:
Location: Koryo Country
Achieved: The Ryanban has the feather stuck into a crystal ball.
Feather 4:
Location: Jade Country
Achieved: It's in the castle, protected by a crystal shell. Kyle Rondart tried to steal this feather, but thanks to Emeraude, Sakura retrieves it.
Feather 5:
Location: Outo/Edonis Country
Achieved:This feather was initially possesed by Seishirou. He doesn't let go of this feather in this arc.
Spoiler! This feather was retrieved in the Nihon Arc (Shunraiki OVA)
Feather 6:
Location: Idol Country
Achieved: The village bunnies possesed it. They hand over the feather easily.
Feather 7:
Location: Shura Country
Achieved: King Yasha's spirit possesed this feather so as to keep figthing Ashura. Once he's defeated, Syaoran retrieves this feather.
Feather 8:
Location: Piffle Country
Achieved: It was found by Piffle Princess Co. Tomoyo-hime instructed her other self in Piffle to hand over the feather to the travelers in her world. After Sakura won the race, she obtains it.
Feather 9:
Location: Rekoruto Country
Achieved: A national treasure of the country sealed in the Library. The group has to steal it.
Feather 10:
Location: Tokyo Country
Achieved: This feather is located under the water reservoir in the Government Building. Sakura falls into a deep sleep, until Subaru urges her to wake up, and she's led eventually to the feather.
Feather 11:
Location: Tokyo Country
Achieved: Once Clone Syaoran has "lost" his heart, he attacks Kamui, Fye and Syaoran Li, destroys the larva where Subaru had slept. The feather is released and Sakura retrieves it.
Feather 12:
Location: Tokyo Country
Achieved: Fuma had the feather in his possesion. But Sakura decides to leave her feather behind, which brings great consecuences in the future.
Spoiler! This is the feather located later on, in Clow Country (Timeline A). Fei Wong uses this feather and puts it into Clone Sakura's body, the last of the feathers retrieved.
Feather 13:
Location: Unknown world
Achieved: Clone Syaoran attacks a new world when the group leaves. He takes the feather.
Trivia
- It would seem that when an artificial human (or at least those created as "clones") dies, their soul turns into a Feather that is able to merge into the souls of the "Originals". Or at least, this is the case with Syaoran and Sakura.