This aspect’s damage increase is negligible.
The tooltip says the character will do 50% increased damage against unstoppable enemies, yet when enemies become unstoppable my damage drops from 400-500k(80%vs stunned) to 100-120k, if I understand correctly it should be at least 250k depending on the math but it seems to be absolutely negligible.
Players often talk about how barbarians are strong in pvp based on our access to the unstoppable status, this would counteract that advantage making things fairer, I also use this in pve to counterbalance the fact that I depend on stuns for damage but it doesn’t seem to be working right now.