My quick thoughts and suggestion on how to improve Red Mage or make the skills a little more fun at least.

Enchanted Melee Combo
Add 500 MP restored for each enchanted melee hit.

Displacement
Potency Removed. No longer shares a cool down with Engagement.

Engagement
Delivers an attack with a potency of 250. 30s recast.
(Using Engagement right now feels fun and I like the animation. It just feels bad that you know it's a worse potency displacement. If it was an actual new skill that you could just weave in but have to be in melee range for, that would be nice.)

Enchanted Reprise
60s CD 10/10 Mana Radius 25y
Delivers an attack with a potency of 300.
Additional effect: Gain the buff enchanted reprise.
Duration: 15s
When the effect expires, gain 30 white mana and 30 black mana.
This weaponskill will not cancel/interrupt any combos.

Regarding reprise... just... something. Even a dot would be fine. Something that could change things up a bit but still keep the same core rotation.