Aether is the divine fire of Heaven and the power that runs through the veins of angels. Empyrean Steel is one substance infused with generic aether, and it is this fire that powers the angelic blades. The power of the aether in angel blades becomes even greater when the spirit of the angel's name is called, imbuing the blade with the power of the angel and causing the blades to glow from within.
Aether can also be exerted from the exterior of an angel or archangel. However, the stronger an angel is, the more potent and dangerous the aether can become to any unfortunate being whom opposes the celestial beings. It is especially prominent when the angels activate their Ascension Forms, for their angelic aura is sometimes accompanied by aether which can vary in appearance and form. It becomes visibly noticeable whenever the angel is exerting effort into their true forms.
The Pleroma, which are owned by the archangels, one of them being the Sword of Michael, also carry aether within them. Using the weapon on a person will imbue them with the divine fire as well, which ultimately burns any form of evil found in him/her; if the person is more evil than good, then it will also burn the life from him/her. Although, the intensity of the aether inside an angelic weapon can be too much for a mere human to wield and thus in the process could kill them.