The Seraphim are Gilgamesh's personally trained unit of Arkn soldiers, similar to a king's guard. They are chosen from individuals who have lost both parents to the War, assuring they will have no reservations in slaughtering any Dekn and have undying loyalty to their leader. They were said to wear only basic leather armor for protection, as their skill was so great that they had no need for metal armor.
History
The first of the Seraphim was Helios, who was an orphan personally taken in by Gilgamesh and trained as a fledgling. Having no claim to the throne, he was trusted greatly by the King and made Captain of the soon to be formed Seraphim. After Gilgamesh's blacksmith suffered an accident at war and was unable to run the forge, Helios stepped up, learning from the old smith and soon surpassing him, eventually secretly imbuing the forged weapons and armor with powerful magicks for the protection of the team. Gilgamesh discovered this and became enraged (as he despised magic), and exiled Helios.
During Gilgamesh's battle against Hash'bor'kanibal, the Seraphim were all killed (save for Phobos) when Gilgamesh, in a show of might, used a series of Hethian Words to cause a massive cataclysm.