This was my fix:
Spell Rage
Your rage is often a cerebral thing, a mental state more than a physical.
Prerequisites: Rage 2/day, ability to cast 1st level spells or use Least invocations
Benefit: While in a rage, you may cast spells, use skills, and use feats as though you were not raging. In addition, at your option, you may gain a bonus to your Key Ability Modifier, instead of Strength, when you rage. This bonus is of the same magnitude as your rage would normally supply to your Strength score. All other rules regarding the use of Rage function normally.
Seems like more of a feat than a class; a class might be created to take further advantage of the combination, though, in a specific barbarian gish type of build.
