"Wait, why are you posting this on the DPS thread? Wouldn't it be more effective as a healer? Don't we have too many DPS anyway?" Yes, I know, but hear me out. This may actually work if you seriously sit down and think about it.
The Red Mage. Jack of all trades, master of none. Enfeebling *champions* back in Final Fantasy XI (as well as being able to do...well, pretty much *anything they wanted to* with certain setups). Ultimately, a possibly broken class to sit down and figure out. Apparently, Yoshi-P would assume that RDM would be a backline, staff-using, support-class enfeebler. While I do agree about the enfeebler status...staves just...don't work for the class, in my eyes. Red Mages have traditionally used swords (*almost* exclusively rapiers) alongside their magical abilities.
So let's play with that notion and introduce a brand new class to the job: Fencer.
Fencer would be what you'd call a very fancy sword-wielder, able to thrust and hit opponents in their weak spots or vital organs. As it stands, we already have a sword-wielding tank in the Gladiator/Paladin combination, but the idea of a sword-wielding *DPS* class wouldn't distance away from other players, would it?
So you have a new Fencer guild, placed in either Ul'dah or Gridania for proper effect. You start fighting with it, you get your first weapon skill, an ability at level 2...
...and then a spell at level 4. Not to mention the help text on both the spell and your first WS have a Combo Bonus on them, listing specific debuffs on them...say, a poison or Paralyze or something.
And when your level 5 quest comes around, the whole idea of Fencer (and Red Mage as a whole) unfolds: by comboing in different attacks and spells in tandem, you gain the ability to place enfeebles upon the enemy, whether it's by striking a vital organ to cause the target to bleed for a bit, or by freezing them in just the right way to slow them down by a little. Later quests come down the road to both train you on these different enfeebles as well as teach you a valuable lesson in the class: as the enfeebles are of a short duration (5 seconds at *most*, but they'd be unresisted to balance it), the only way to keep them consistently up is to alternate both the specific WS and spell in order to keep those debuffs upon the opponent. The moment you let up, it restarts. Give it abilities to help buff the next enfeeble landed in either potency or duration, and throw in a few extra abilities that either increase physical or magical damage, while *possibly* decreasing the opposite in turn.
And *then* comes the unlocking of Red Mage. Assuming the lore behind it, you could make the unlock requirements FNC30/THM15 (optional job being CNJ), to give it abilities and spells from both the White and Black "schools" of magic. This is when RDM becomes on its own. Give it a starting ability to immediately place an enfeeble from any spell or WS from the get-go, to speed its duties up that much more. Anything after that could include its own Convert or Refresh ability (so it can keep up with its own MP consumption, although spells could have somewhat lower MP costs to counterbalance), its own party-wide buff spell (increased Determination or the like), and a final ability that enables it to immediately throw out move after move with only a split second's wait on the GCD (something akin to Chainspell from FFXI, although *severely* nerfed...think River of Blood and Perfect Balance).
Gear-wise? That's where the "JoaT, MoN" mindset that RDM is *known* for comes into play. Give most of its unique, left-side gear a mix of either primarily STR or INT, to buff either their melee or magic capabilities. Allow players to either choose going into their melee side or their magic side for competent damage-dealing, as most of their spells and weapon skills would straight-out deal damage. That, and their debuffing prowess wouldn't be hindered by either of these, thus allowing a few different play styles to come out of this.
Do you throw yourself to the physical side of things, and get the most bang for your buck on your weapon skills? Do you consider yourself more of a caster, and focus your damage more on your spells? Do you choose to go straight down the middle, being decent at both, but not *excel* at either? It's all up to you. You are the Red Mage. *You* choose your path you want to go. And, regardless, you'll still be enfeebling enemies as you land attacks and spells...while having plenty of fun while doing it.