Aegis is a Relic weapon.
There are 5 items that share this name:
Please follow the above links for more information about the item. Aegis can be upgraded via Weapon Trials.
The Aegis in the book of Iliad is the Shield of Zeus, although it was sometimes lent to Athena and rarely to Apollo. The shield was built with the hide of the Amalthea (Amaltheia in FFXI), and was decorated with golden tassels along with a gorgon's head (from the gorgon Medusa) mounted in the center.