imo to keep concepts as open as possible and to avoid biblically implied power creep, I would suggest keeping the angels as generic as possible in regards to specific denominational paradigm or ranking hierarchy, similar to how Demon Summoning is handled.
perhaps some 'lil motes of golden Light or ephemeral pillars of Fire that fire beams of energy that inflict -tohit for T1, some mysterious robed figures with ranged in and some kind of res or dad buff they can cast on the mm and fellow minions for T2, and reserve the model with wings and a fiery sword and burning crown or an Owl's eye surrounded by interlocking circles and triangles for the T3, a melee powerhouse maybe with some kind of damaging aura.
while the instinct might be to give angels some kinda healing or ressurection-like powers, let's not forget that typically they are seen as destroyers and messengers first in most mythologies, and are the original source for the demonic in abrahamic traditions...