Castiel wasn't relaxed or had even dropped much of any tension, but he didn't seem as frustrated anymore either. "Working with Nakama's power makes focusing mine less strenuous." It took less effort and strain to concentrate and focus so carefully, which made it easier to do, at least on the ones he was practiced with. The larger wound from before he was beginning to think was simply an issue of skill in not knowing how much power to use in the first place.