Trey of Swords is not actually a novel. It’s a micro-trilogy: three interlinked and consecutive novellas. The viewpoint character of the first two is Yonan, son of a Witch of Estcarp and a Sulcarman, and the third novella is narrated by his lifelong crush, Crytha, an untrained but powerful witch.
The chronology is interesting, because it happens shortly after Three Against the Witch World, while Kemoc and Kaththea are off dealing with the events of Warlock of the Witch World. Eldest Tregarth triplet Kyllan plays a role, and he and Dahaun are very much an item, but the other two are busy elsewhere. I kind of enjoyed seeing Kyllan from the outside, and watching him be competent and in charge, though of course Dahaun rules.
I did not remember this one at all.