Aegis (聖盾, Seijun lit. Sacred Shield in the Japanese version, Égide in the French version, Egida in the Italian version, Égida in the Spanish version) is a skill introduced in Fire Emblem Awakening.
In Awakening, Aegis halves damage from Bows, Tomes, and Dragonstones. The activation is (Skill)%. Aegis will not activate from Dual Strikes. This was changed in Fates, and it can now activate on any kind of attack with those weapons. It is learned by Paladins at Level 15.
In Heroes, Aegis is a special type skill which halves damage inflicted by attacks from foes two spaces away.
Aegis (from the Greek Αιγίς), as stated in the Iliad, is the shield or buckler, or breastplate, of Athena and Zeus, famously bearing Medusa's head, which, according to Homer, was fashioned by Hephaestus.