I honestly feel all the Witch Hunters needs is Follow My Path on Stalkers and a complete rework of Thalarian Quellers.
Samael could have a positive to attack versus burning targets but that's about it and I don't think it's that necessary
Thalarian Quellers could have:
AoE Shielded
Giving Focus (something like Weird Device/Strengthen Armor)
Tools for the Job
Analyze Weakness
Way to remove suits from enemies
Remote counterspell (if you want to declare a trigger within X of a marker, you have to discard a card)
Gravity Well
SS usage disabling
Right now they are neither a support piece, a control piece, a tank piece, a damage piece. They are just all over the place.