Back on topic though, this needs to be tested. Soonerjbd you have a sorc and sage correct? Can you test both abilities in a duel and see which is there is any targeting difference?
I tested this tonight in both PvP and PvE, and I can confirm what Methanos has said.
As a Sage, you can be running away from someone and cast Sever Force. As a Sorc, when you try this it says "Not facing target" in big red letters. This appears to be a bug one way or the other.
Affliction and Weaken Mind can both be cast while facing away from the target, so they are working properly.
Please send a bug report on this in-game. If many people do so, it increases the change they will fix it.