The sequel to Have Sword, Will Travel. Spoilers for that ahead.
It opens with Odo and Eleanor, and Biter and Runnel, running to fight bilewolves, who are attacking two travelers and others. Sir Halfdan fights, and dies.
And one traveler, they realize, is Edga -- the king who abdicated. Soon after, an Instrument (a new title) arrives to take over the role of steward. Edga with their help puts him down, but obviously, he must see to his grandson, the rightful heir, and his grandmother regent.
It involves spelling, the nick in Biter, craftfires summoning creatures, a machine to control the weather, and more.