How Would You Design Red Mage!?

[SwordCoheir]

That could work within a cleric stance kind of setup. I know I'm stealing from SCH in FFXI here but something based around

Light Arts- White Magic potency boosted by 20%, Black Magic Potency, Attack Power reduced 20%.
Dark Arts- Black Magic Potency boosted by 20%, White Magic Potency, Attack Power reduced 20%.

And naturally make Fencer / Red Mages melee capabilities superior to their magic abilities, if anything just to keep from having a third stance to take up an extra action bar slot.

Some of my initial fears with RDM is if we let the magical and melee aspects remain separate from each other, one side may end up becoming overly favored over the others (similar to FFXI), or too powerful. With some kind of focus like that, it might keep the versatility aspects of RDM from being too powerful while letting the magic and melee side stay separate. Just maybe though.