The Price of Blood and Honor by Elizabeth Willey

A powerful fantasy novel in its own right, set in an expansive and complex fantasy universe, The Price of Blood and Honor brings to a grand climax the tale, begun in The Well-Favored Man and A Sorcerer and a Gentleman, of the kingdoms of Landuc, Noroison, and Phesaotois. The bitter, centuries-old feud between Emperor Avril and his wizardly brother, Prospero, has broken into open warfare, and events and armies are unstoppably on the move. In the midst of all this, Prospero's two grown children - staunch, unworldly Freia, and her urbanely sorcerous half-brother, Dewar - find themselves thrust into the very heart of the action. The Price of Blood and Honor is a rich, complex, and splendidly high-handed work, full of epic tragedies and comedies of manners, wars and romances, primal acts of creation, gritty military details, intricate espionage capers, talking animals, mythic beasts, ducks, and a great deal more besides, in the story that is the climax and completion of this series.

This book is part of the "Argylle" series.
Here are some other books from this series: