Zora: Daughter of Thunder

In this world a prophecy names one supreme divine child who will save a declining Divine Race, and every prince born to King Vos must pass a trial to claim the title. Vos's three pure-blood sons all fail it. The one who awakens the power, supreme thunder, is Zora, his half-human daughter, who has been working as a temple maid. Queen Mera, Zora's mother, has been hiding a strength of her own for years and lives as a slave in the palace because of it. When the Sea God Neros invades, Mera is wounded defending the realm, and Zora finally lets her power loose in the open. Neros uses the attack as leverage, forcing Vos to strip the divine bone from his own daughter to appease him. Mera sacrifices herself so Zora can escape, and Zora falls, half dead, into the Demon Realm, where she is found and kept alive. Three years pass. Zora rebuilds her strength in exile and returns to a Vos who is now repentant, his own bone reforged into a weapon for her to carry. She goes through five trials, kills Neros, and travels into the Deep Sea Hell to bring her mother back. Along the way she also faces Hades. Vos abolishes the pure-blood law that had barred her from the throne and names her Goddess of War. Mother and daughter are reunited.