you know what’s kind of astonishing about 5.08 and Castiel?
that Castiel was so determined to get at the Winchesters, that he flung himself so hard and so repeatedly at Gabriel’s defenses, that he probably was prepared to shred his vessel to get through.
of course, Castiel’s injury could have been the result of another of Gabriel’s tricks, but that’s… not really his style. Castiel wasn’t part of the lesson he was trying to impound after all, so beating him up would have just been exerting a needless amount of energy. when Castiel first finds Dean and Sam in that japanese gameshow, he says they’ve been missing for days, which means Castiel’s been looking for them for days. and so when he finally finds them, he throws everything he has to get back to them.
maybe he didn’t even expect to be able to break through, going from his surprised look as he comes through the door, but he would have thrown himself at that wall, no matter the injury sustained, until he couldn’t, all the same.