Regular first aid is not really Hazel's thing. She still wasn't used to not having her mother around to instantly heal anything worse than a small cut. That's why she fishes out a potion and decides to give it a shot instead of trying to mess with bandages.

And while she's close she'll try to feel out the injury with magic even though she's not really good as sensing things that way yet. Failure was quite likely there.

Hopefully no one will notice if she seems to space out for a few seconds. She'd rather not try to explain what she's doing if it doesn't even work.