So, as far as I know, seers suffer from their aspect, too. Just not as bad as mages. Maybe, a seer/mage of mind can be very self-destructive or with a mental illness? I really see them dying from their own poison

I think a Seer and a Mage’s suffering is intrinsic to the nature of their powers, I mean if you’re able to see outcomes or futures, you’re bound to see things you would’ve rather not have seen, or wonder if you could’ve prevented something you saw some way. Also we do see a Seer of Mind, and her poison is, indeed, regretting her Choices.