I wonder if his "breathing" will actually be a useless skill and not the classic trope of "skill that only appears useless unless you think about its use for 5 seconds". The guild girl did say that it's a common skill for people to get, so I feel like if it had a different application it would be known by now (like if how you level up just by breathing like the other user said, all people with breathing skill would be super high level)