what exactly is the lore of Uriel fron Roathe?

the lore from roathe is kinda confusing. does he actully n

mean there was a whole army of uriels, but i feel there shouldve been more than just the one locked up no? and is he eluding to a uriel prime possibility, since i thought primes were single origional frames, but obviusly an army of uriels would conflict with that. what exactly is Uriels lore?