[Kuritza]

Dont equip Wraith lords if you use them whithin your domain as raiders/thugs. Just give them some cheap bodyguards like militia and place them far from the enemy. Sould vortex will devour bodyguards, remove fatique from wraith lord and kill enough enemies to make them run.
Maybe something really cheap, like a pendant of luck. Thats the beauty of it - these guys cost a lot, but after you've paid for him, you can sent him into battle right away and you dont care if he dies.