Rarity is an indicator assigned to each hero in Fire Emblem Heroes which determines their starting stats and unlockable skills. Each hero has a range of rarities from 1✯ to 5✯. Heroes obtained through summoning method have a range of rarities from 3✯ to 5✯.
Rarities lower than 5✯ can be increased by the Unlock Potential option available in game. Originally, the unit needed toreach a minimum of Level 20 to Unlock Potential, but the requirement was removed in version 2.9.0. The player then expends a set amount of Hero Feathers and either Badges or Great Badges to increase the unit's rarity. If the Unit has merged with a Unit of the same rarity, thus having a bonus level, the maximum required Feathers to upgrade drops a slight amount. Upon raising their rarity, the unit resets to Level 1 and has all of their stats reset to its base. Only SP and Acquired skills do not reset upon raising their rarity.
|1✯ → 2✯||5 Badges that match the Hero's attribute color|
20 Hero Feathers
|2✯ → 3✯||10 Badges that match the Hero's attribute color|
200 Hero Feathers
|3✯ → 4✯||20 Badges that match the Hero's attribute color|
2,000 Hero Feathers
|4✯ → 5✯||20 Great Badges that match the Hero's attribute color|
20,000 Hero Feathers