Castiel's breathen is definitely ragged. The last few hits made him cry out, but the break is giving him time to calm himself, get his bearings together. His body doesn't just ache, it hurts, badly so, and Castiel makes a frustrated sound as he shifts his weight, tries to alleviate the pressure.

He can do more. This is only a little further than they've ever gone, and he knows he can do it, knows he has to. Owes it to Sam, owes it to the thousands who died and suffered at his hands. Castiel's throat burns from the misuse of his voice, but once he finds his footing again, he stands steadily enough - waiting for more, willing to push himself through this, determined to make it, to not disappoint again - even if he has it wrong as to what would constitute a disappointment at this point.