The sad thing about a mage is that they don't have a tank that takes the damage for them while they are in battle so therefore they take all the damage.

Am I just not upgrading my armor like I should be doing?

Are mages more like Paladin's and Hunter's than they are warlocks? Unlike warlocks, do they need to actually upgrade their armor score manually like all melee fighters do? Is armor of great importance for mages like it is for melee warriors?