Beguilement (The Sharing Knife, #1)

Alternate Cover edition here.

Troubled young Fawn Bluefield seeks a life beyond her family's farm. Enroute to the city, she encounters a patrol of Lakewalkers. The necromancers armed with human bone knives fight "malices", immortal entities that draw out life, enslaving humans and animals. Dag saves Fawn from a malice - at a devastating cost. Their fates are now bound in a remarkable journey.