I believe this is right on.

If you were going to do anything I would recommend giving mages a boost to their spells.
Or atleast a higher % chance of landing a "big hit" off a spell at lower levels.
A critical hit of sorts. This would give a mage more of a classic glass canon feel.

Other options:
Nerfing dual wield at lower levels slightly.
Nerfing higher level gear on lower level characters.
Giving mages a lower level protective spell that might deflect blows more than on occasion.
Ex: Armor of Bone, Sheen of Stone, etc. Of course these would have to be made inert by higher level protections.
Give healers a damage attack other than kick. ;)
Give all mages shield block and Transmuters dodge. :P

I hope this helps some.