Claw doesn't have to mean melee attack :P We just happen to have a claw slot, and can smack stuff with it...'claw means melee' is no reason to not give casters an epic claw made for them. In a lot of the animations, it looks like the paw/claw is what's used to toss the spell out. *gestures at bolded part* It does amuse me when I think of my caster dragon with her reklar tail scale...wiggling her butt and out pops a mighty spell.
With that said, I'd much prefer an epic caster claw. However, it'd have to be better than (someone correct me if I'm off/wrong) Primal Rage + Drulkar's Flamestone + 15 spell dps (and Ithink there's some to-hit in there too?). I messed around with my caster claw some and that's the best combination I could come up with, so any epic would have to be better than that.
On a side note for the claw, since it would be for casters, the base damage of the claw itself could be lowered in order to allow the caster-buffing parts of the claw to be improved.