Savage Fang Ojousama: Shijou Saikyou no Youhei wa Shijou Saikyou no Bougyaku Reijou to Natte Nidome no Sekai wo Musou suru

Mylene has it all: She's the daughter of nobility, she boasts incredible aptitude with magic and the blade, and she possesses striking vermilion-tinged locks that signify she has been chosen by God. Yet this elegant warrior hides a shocking secret—inside her lurks the soul of the strongest mercenary in history, Savage Fang. In his past life, Savage Fang cut down countless foes of superior ability for his employers with nothing but cunning and strength. Now reborn as Mylene, this former sellsword will use her past experience and newfound powers to shape the world as she sees fit...even if she has to get her aristocratic peers involved along the way!

(Source: Yen Press)