Tenshou shita Dai Seijo wa, Seijo de Aru Koto wo Hita Kakusu

Fia, a girl born to a family of knights, was told that she had no talent for the sword. As she laid dying from her trial, she recalled her past life as the "Great Saint", with extraordinary cheat-like magical abilities. With her newfound skills, she could heal herself and tame a mighty black dragon to become her familiar. But she also remembered that in her previous life, she was tortured and killed by the demon lord's right-hand man. He warned her that if she ever dared to reincarnate, he will hunt her down and kill her again. So Fia resolved to hide her Great Saint identity, and become a normal knight instead. But her new skills caused quite a bit of fuss anyway?

(Source: Comic Earthstar, translated)