Warrior mace specialization doesn't work?

[BarnabyJones 0]

I've been grinding for some time and noticed that I've never gotten a single proc on the 3 sec mace stun for warriors in the arms tree. Any chance this just isn't implemented or something? Not sure what I could provide to help sort this 

[BarnabyJones 0]

Nevermind I'm just unlucky, please remove