Oath of Fealty by Elizabeth Moon (Random House, 2010).
This novel is set in the fantasy world and time of Elizabeth Moon’s earlier series which began with Sheepfarmer’s Daughter, but involves different characters. After you adjust to all the myriad names of places and people, and weird new labels for ordinary concepts (like “glass” as a unit of time), it becomes pretty absorbing. The author has clearly put some thought into the religious structure of her fantasy world, defining not just good and evil but entire sects that follow each path. The characters seem to truly believe in their respective faiths, not just go along with them the way they do in many fantasy worlds. They also take seriously their oaths of fealty to their dukes and kings; this is not a world of cynics like the folk in A Dance with Dragons. It’s also very much a military novel (like all of Moon’s books), with a lot of day-to-day military stuff like sword drills and patrolling the countryside.