I understand and agree with all your points. I will however double down on damage weakness being really really strong (we obliterated a solo with my group yesterday with just the damage weakness 2 from the Warrior Priest kit), so I would at a minimum make it save ends. For the insta-death ability, many people in the community say that YAAD is way too strong, while Censored's condition to work (hitting the target just before winded to make it winded) makes it way less strong than the other one.
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I wasn't aware YAAD was a sore balancing point for the community, so that's good to make a note of. As far as damage weakness goes, I suppose a smart group will get tons of use out of it if they focus fire for a round, so adding save ends or ends after the retainer's next turn would work (assuming I keep it, I'll take another look at that as well.)
Thanks for the reply and all the feedback! It's been very helpful.