Fangs of the Black Tiger by J.F. Lee
Tales of the Swordsman book 2. Serious spoilers for book one ahead.
Our swordsman and the magistrate who is the only other survivor of his school, and a merchant woman who was with them, are recuperating and trying to find out what happened to the girl who traveled with him, and whom he finally admits is his (adopted) daughter.
Meanwhile, her captors run into trouble.
This involves monks and their monastery, the magistrate's history, the girl's admitting she can't read something to a dangerous man, sworn sisterhood, a boy who justly hates his uncle, and more.