I couldn't sleep so I whipped up an idea of what the base fencer class could be that red mage could use as a base class with my previous red mage job idea.
I made the fencer to be a duelist. Something that works with one opponent, but has trouble with multiple.
Lvl 1- Lunge - Basic Front WS
Lvl 2 - Retreat - Slide backward and regen Hp. Fades upon being hit.
Lvl 4 - Reprise - After you are Parried/Missed WS
Lvl 6 -Passata-sotto - Increase chance to dodge single target enemy
Lvl 10 - Shadow Stick - Combo off Lunge: Bonus Heavy on target
Lvl 14 - Appel - Taunt
Lvl 18 - Riposte - After Parry WS
Lvl 22 - Finesse - Increase Crit. Rate buff for next attack
lvl 26 - Featherblow - Back Attack WS
Lvl 30 - Swarm Strike - Combo off Featherblow causes poison: Bonus Increase poison duration
Lvl 34 - Engagement - Auto-attack against target increase TP generation
Lvl 38 - Disengage - Lowers damage from single target enemy when holding highest enmity
Lvl 42 - Fleet of Foot - Removed heavy and if heavy is removed grant movement increase
Lvl 46 - Swallow Tail - AoE WS Combos off Shadow Stick: Bonus turn to single target multi-hit attack
Lvl 50 - Check Mate - Ws combos off Swarmstrike: Bonus: Greatly increase crit damage.
EDIT: For easier reading. All in one spot.
Red Mage:
Cross Classes: THM and CNJ
1) Mage Stance - buff like cleric stance - Lowers melee damage, increases all casting stats (Healing pot, M.Acc, ect) and grants refresh. With a fencer being base, red mage would be a weaker caster. This so the Red Mage can shift to nuker/healer on the fly.
2) Double Cast - Classic Red Mage ability - Cast two spells, even different ones, using the same cast time.
3) Omni-Spell - Elemental-less nuke - I would have this spell combo off any attack spell and takes effects off the nuke which it was combo from. (Example: if combo-ed off fire become a fire damage AoE or if combo from thunder does singe target thunder)
4) Spellblade - I made it up be goes with theme - WS combo effect gives a buff that makes next spell cast free of mp cost and insta-cast.
5) Chain Spell - 15 min ability and classic red mage ability - For duration of the buff all spells have no cast time or cooldown
Keep in mind. I have not played FFXI and do not see Red Mage as a Debuffer/Buffer. I see red mage as melee that can cast low level white and black magic that has quicker spells to make up for weaker spells.