Nice to see that the angel-theme with quincies is continued and Allon, considering he was strong enough for yama to step in is quite frankly thing I hoped to see again.
So I guess the forms those "quincies" use are closer to the Magic Hunters of the old.
now I would not be surprised if Royal Realm is indeed a jail. If "quincies"/Magic Hunters ruled SS before shinigami and shinigami overtook them, somehow sealing in the "Soul King" and keeping him sealed through some means(feeding the lock shinigami?) it would certainly explain it all. It would also explain the angel-like appearance of quincies, including the idea of them using archery(the thing associated with angels) as well as why shinigami are thematically "demonic" in contrast to "angelic" quincies.
So I guess the "magic hunters" are the original Archangels and quincies are in sense, their servants, humans given angelic power, just like in the actual hebrew lore.
Which makes his eyes fit too, since anyone who looks upon archangel would either go insane or get his eyes burned out by the horrifying presence in the mythos.
Also gotta love smart and stable Ichigo. He is not even going bankai yet and the whole thing did not even seem to injure him and he is trying to find out stuff about whose quincies, etc. so he does not have to make the first move, nor rush blindly.