Would it not take damage or just super strong but do able?
I've encountered a random bug on bosses (random as in different bosses and inconsistently) where they don't take damage. Anything like that? Did you re try it?
All my characters use heavy armour....impenetrable...
I defeated the grand sermonizer with a level 6 bosmer nb. Shouldn't be any problems
You have not been "nerfed"
You use all heavy armour + impen. There is yor problem. You simply don't have the damage you need to beat that boss.
Basicly you are running with a PVP setup, trying to do PVE and that wont work.
As @Runs already said above...
Level shouldn't really matter much since you're scaled.
You probably need to work on your rotation, skills, gear etc. ...
I'm having a lot of problems because she doesn't have just two adds, I count 7, ya, 7. How are you supposed to be able to take out 7 adds, while dodging her attacks? One on either side of her, two out front, two off to the right, and at least one on the left. Even engaging just the two out front from a distance, aggro's all of them.
To comment on this.
You can't use the blade of woe on characters with unique health bars ("Bosses") or characters that do not represent the races of Tamriel. e.g. Daedra, Sload, Animals, Giants.