ok, the thing is its not 500 damage, that would just be 10% block chance. My first shield came with an 18% block chance, 18 x 50 is 900 bonus damage per swing, and thats just base damage, the skills are critting for 2.5k, Im not sure what kind of top level shields exist but a 50% block chance shield is going to give a 2500 bonus damage, you combo this with a fast weapon like a dagger and a fast firing skill then suddenly this feels like it could be breaking the game balance.
So this is great if its intended and balanced for the end game, but as I alluded to in my OP, its completely trivialised the campaign. Bosses went from being tough but fair, to being 3 shot from my flying hammer.