The first with the title Archangel was a Covenant general named Takarrûs. He devised a system of Angel Ranks that afforded power and prestige to those dedicated to the cause. The last rung of this ranking is that of Archangel, one step down from being a Cult Power.
One does not just become a Higher Power with a snap. They have to accumulate a certain number of worshipers, the fuel, and then be Ascended by the judgment of others. Be they The Balance or other faction, you either get in by influence or taking out another Higher Power. The latter being the Rule of Divine Conquest.
We mortals have our place on this board. Pawns for some, not on the board for most, and for the rare few, divine champions destined to fight on the battlefields of the gods.
In both the Creation War (1486 DE - 8777 DE) and the Demon Spawn War (8972 GE - 9493 GE), archangels led many armies against their primordial and demon foes. Many of the greatest of these leaders went on to become Higher Powers.