The Ascendance of a Classless Princess

Isabel Rigris, despite being the third princess born from the Royalty of strongest Empire of Faron, the Rigris family, she was known to be very coward. She never hold a sword in her life. After reaching the age of Class identification ceremony, she was been determined as classless. Someone who can't wield mana into any form. Being classless as well as having a rare white hair and silver eyes features this further makes her a source of disgust to the family. Then one day she was forcibly sent to a mission to subjugate goblins in the forest together with other problem childs of other noble families to awaken their talents through life and death situation. But never been in their wildest dream that they will be attacked by the demonbeasts. And a Demon general took fancy of Isabel and injected her an unknown ability that made her a monster on rampage. What will be the fate of a useless princess that was been a recipient of an unknown ability from a demon General?