I was reading this manga or manhwa, I forget. But there 2 saintess, and one was a mage and the other one was the real saintess. But the first prince mistook the mage as the saintess. The real saintess was in a group of making potions, and her skin got better because she liked what she was doing. I read all of the manga, it’s just that I forget the title lol.
I think it’s this one
http://www.mangago.zone/read-manga/seijo_no_maryoku_wa_bannou_desu/
umm what the hell 16 yrs old nahhhh………..