Give Raise to all the casters;
Red Mage gets Verraise and Dualcast, for rapid Raise.
Summoner gets Flames of Rebirth, which Raises the target and does moderate Fire AoE damage around them, for not entirely DPS loss Raise.
Black Mage gets Walking Dead, which Raises players with the Walking Dead status effect, and needs to be dispelled the same as on Dark Knight (Necromancer theme was the only way I can think of making Raise work on Black Mage).
Blue Mage gets Reraise from Lost City (Hard).
Done. Now Raise isn't special utility for Red Mage which holds the Job back in other aspects, it's effectively a Healer/Caster role skill. Except it isn't a lame role skill, it's something that provides some level of class identity, which this game is increasingly desperately lacking.
The moment Red Mages Shadowbringer kit was announced I was incredibly disappointed. It really is a lackluster kit... I really want two things form Red Mage going forward;
A bit of an emphasis on the sword side of things. Reprise and Engagement almost provided that, but Reprise and Engagement are also things you really don't want to use all that much... A rework for the crystal swords gimmick would be nice too, I actually think that could have a gauge element applied to it. It's a fairly cool concept that's just wasted on a oGCD IMO, I'd rather have it as something to manage, perhaps with a visual element to it given Red Mage is one of the only Jobs with no visual "stance". Certainly the only caster, Black Mage has Umbral/Astral, Summoner has its pets, even Blue Mage has Moon Flute... Dragoon has Blood of the Dragon, Monk Greased Lightning, Ninja gets a shadowclone, Dark Knight has Fray and Darkside... All great visual effects for part of their Jobs rotations, and Red Mage has nadda... Spin some crystal swords around me like this is FFXV, that visual was perhaps the only good thing about that game after all...
A different way to look at the existing gauge. Right now it's fairly boring... There is an aspect they could expand on though, and that's the unbalancing of the gauge. Right now that's solely a punishment mechanic, but I think it would be interesting if it was something you intend to do for part of the Jobs rotation. A DoT, for example. Something you don't spam but need to reapply all the same. Make it a sword skill like Reprise that uses up Mana gauge, if you have too much White Mana, it applies Verwater, if you have too much Black Mana, it applies Verblizzard, with it costing a specific Mana to rebalance you (so if you apply Verwater, it costs White Mana to bring that down to rebalance). Then we have the exact same gauge, but we're using it in a new way.