The problem i'm having with it is i'm wearing a full set of armor as the game describes is so people DON'T know your undead because if they did they would attack on site. So without lowering my physical armor to 0 and casting decaying touch they can just go right in and "heal" me. They should at least have to realize i'm undead (use decaying touch and see it doesn't work) before trying to heal me, otherwise they would be assisting the enemy. Not sure if this was even noticed before or maybe overlooked because undead wasn't in the early access.
It is the the same problem with Glass cannon tough. AI is to much all knowing and getting killed by getting killed is kind of no-brain-easy because no armor can prevent it.
I'd argue that enemies, such as players, can "Examine" you and realize you have the Undead talent or the Glass Cannon talent and exploit that. It seems fair, because players can heal enemies with the Undead trait and deal damage that ignores their armors as well. I don't know any enemy with the Glass Cannon trait, but the players would be able to exploit that as well.
To avoid making players outright stronger than creatures as you suggest, there could be an item (perhaps even Fane's mask itself) that hides your talents from enemies, so that the AI can't exploit those while the character has that equiped.