The Council of Blades

A deadly new weapon may change the nature of war forever in this fifth installment in the Nobles series
 
War cares little for the troubles of the aristocracy—as a motley crew of nobles and commoners, humans and other creatures are about to find out. Though the city states of Sumbria and Colletro, warring regions of the Blade Kingdom, have reached a truce, the battle is not yet over.
 
As a terrible new weapon obliterates the age of courtly battle, an intelligent princess with burgeoning magical powers—along with an addled young inventor and kleptomaniac firebird—finds herself forced into a battle for survival in a world far deadlier than the one she has known.