Archangel Michael

Archangel Michael (神の如き者 (ミカエル) ) is an angel who is known as "The Likeness of God". Fiamma of the Right, the leader of God's Right Seat, is aligned with Michael. It is said that the sword Curtana has power equaling the powers of Archangel Michael and that the wielder, the queen, acts as the leader of the angels while the knights themselves act as angels.

Background
Archangel Michael was created by God to defeat the malfunctioning Lucifer. Michael defeated the legions of fallen angels and Lucifer himself, casting them down with the power of his right hand. He then assumed the position that Lucifer formally held, that of leader of the angels.

Michael is said to wield a flaming sword.

Document of Constantine Arc
During her interrogation, Lidvia Lorenzetti says that Michael is the being with the highest-level power and was created to oppose the Fallen Angel Lucifer. Then, she adds that God's Right Seat believe that Michael defeated Lucifer, who sat to the right seat of God, and became the ruler of all the angels, but implies that this might not be the whole truth.

British Royal Family Arc
Queen Elizard presents Curtana as a sword which provides the bearer the power of Michael, the leader of the angels.

Coronzon Arc
During the final battle between the reproduced Mathers and Aleister Crowley, the former manifested the four archangels representing the elements, including Michael, however they were immediately dispelled when Aleister used a spell to banish Uriel, which dragged the others down along with it.

Abilities
Though Archangel Michael himself has yet to appear, the extent of his power is suggested by his background, the immense powers of fellow Archangel Gabriel and the power displayed by the Curtana, which was drawn from him.

Trivia

 * In the Abrahamic tradition, the archangel Michael is commonly perceived as one of the highest-ranking angels and ranked as the commander of the army of God.