Shamsiel is the angel of day, and the sustainer of all light. At sundown, Shamsiel "dies" with the sun, and walks the Road of Resurrection throughout the night to protect their realm and the mortal world from demons. Once they have proven themselves worthy through their battles on this road, they will return to their realm once more with the sunrise. Shamsiel shares their realm with their counterpart, the angel of night.

Shamsiel's name takes inspiration from the Arabian sun goddess Shams, and the biblical angel from the Book of Enoch with the same name, Shamsiel, who teaches humanity sun signs. A lot of Shamsiel's duties in the Overworld is also reminiscent of the Egyptian god, Ra.

Reference Sheet Terminology:

Virtue - The elements in the mortal world that angels gets their power and inspiration from.

Watcher - Their archangel creator, and who an angel primarily serves. All watchers are the angels created by one of the three primordial archangels.

Class - A rank for angels in relation to their virtue. Wardens are the most powerful of the watchers, and are considered the "right hand" to their archangel creators.

Angelic Beast - The animal form an angel takes when entering the mortal world.

Counterpart - An opposing virtue of an angel that helps maintain the balance of both virtues in the world. Neither of these virtues could properly exist without the other.

Weapon - Preferred weapon an angel uses in combat.

You can read Shamsiel's comic here.