A Fate Forged in Fire by Hazel McBride

Aemyra has always known she is destined for more than the life she leads as a blacksmith: gifted with fire magic from the Goddess Brigid, she is the first female heir born to the throne of Tìr Teine in two hundred years. But her father has kept her identity secret while he has been in exile, waiting for the right time to put his plan in motion.