Whatever you do, avoid the last one— The Knight & Knave of swords. It’s god-awful. Kinda soured me on Lieber, to be honest.
The Sadness of the Executioner was written in 1973. I would be more forgiving of the nastiest partFrom what I recall, Mouser gets worse as time goes on. I'm not sure it's intentional on the writer's part. It doesn't seem to get called out at any point but he does turn into a nasty piece of work. I didn't get through The Knight and Knave of Swords, but it's already there by The Sadness of the Executioner.