Est is a playable character in Fire Emblem: Shadow Dragon and the Blade of Light, Fire Emblem Gaiden, Fire Emblem: Mystery of the Emblem, and their remakes. She is 16 years old in Fire Emblem Echoes: Shadows of Valentia.
In Takayashiki Hideo's unofficial Mystery of the Emblem novel adaptation, Est is 17 years old.
In Fire Emblem Awakening, Est is the first DLC character for the Second Series DLC Pack and was illustrated by Kinu Nishimura.
(Source: Fire Emblem Wikia)