The hierarchy of angels consist of 4 ranks:
KAEV
Seraphim
Archangel
Virtue
Virtues are the most basic tier of angels. They are only allowed to leave Celestia if accompanied by an Archangel or any higher rank.
Archangels are a higher rank than the basic virtue. They are allowed to leave Celestia into LIMBO and usually fight off the ABNORMAL or members of the SINDICATE.
When an angel is swooned, they fall into insanity and lose sight of who they are, heavily mutating their physical form into cosmic horrors.