I can't get my demonology warlock artifact weapon

[Boros]

Hello, hello, I have a huge problem and that is that I cannot obtain my demonology sorcerer artifact weapon. I already did all the corresponding class missions and I still can't get my weapon. Please help.

 

[Restlessness]

Hello!
You need to find npc O'Shea, he is located in Dalaran, and buy artifact on him.