In Before The Storm they mentioned some examples:
-holding it supercharges your mind. Inventions, tactics, anything you can put your mind to.
-has shown incredible creative and destructive power. From purging poison and healing to annihilating and killing. It just depends on the input.
Basically if you can do it, azerite will improve it. There's nothing like it.
Gallywix having it is particularly concerning. Either by its ability to make him even more deviously cunning and manipulative or just him having an insanely powerful gun hiding in his cane that he could casually vaporize people with.
They took over literally the entire world. Every order hall campaign addressing dividing and conquering different wings of it using the artifact weapons to be strong enough to push it back. And it's pretty safe to assume while we were partying on Argus the nonstop stream of legion ships in the skybox kept Azeroth pretty busy.