Oathblood is a fantasy novel written by Mercedes Lackey and published in 1998. It is set in a medieval fantasy world, and follows the adventures of a mage and a warrior, Kethryveris and Tarma Tal'se'drin. respectively. After her clan of nomadic fighters was slain by bandits, Tarma swore herself to her Goddess, and began a quest to eliminate the bandits. On the way, she met Kethry, who helped her to complete her quest and the two were bonded together by the Moon Goddess. This book is the third of the trilogy (Oathbound and Oathbreakers were the first two), although because all three books are really collections of short stories, the order is quite irrelevant.
I enjoyed this book, and found it to be well-written and interesting. However, there does seem to be a bias towards the female sex, which is understandable given the normally subservient roles women take in traditional fantasy. I think this bias is a little too obvious in places during the books, and at times you are left wondering whether they will ever find a kind and pleasant male character. But this is corrected during the later stories, and does not seriously detract from the impact of the novel. It's not amazing, but it's well-written and deep enough to be an enjoyable experience.