When I think about glass cannon, I oftentimes end on the same conclusion than you: I'd simply nerf the bonus amount (and vitality malus). But I'd intuitively go with 20% or 25% instead of 50% (compared to original 100% bonus).
Having a resistance tradeoff that is not just HP (vitality) might be a good idea, I guess it depends whether you think talents should have tradeoff or not (some have, some don't, why?).
I'll have a look at your artifacts mod.
