Everything you need to understand or teach Daggerspell by Katharine Kerr.
Daggerspell begins the story of Nevyn, a disowned prince, who becomes a master of the magic art of dweomer. He does so to atone for his youthful indiscretion that resulted in the disgrace and death of those nearest to him and his own banishment.
The first part of the story takes place in the seventh century, when Nevyn (then named Prince Galrion) is torn between the girl he loves and his desire to study the magic discipline of the dweomer. He inadvertently causes his betrothed lover and her brother to engage in incest, leading to their deaths, as well as the death of a rival suitor. Prince Galrion is disowned by his own father who now calls him Nevyn (which means "no one"), and he is cast out forever from the privileged noble class. He makes a vow to never rest until he atones for his errors, and...