What of you combined the Spellblade concept with the ever-popular suggestion:
Runic
One minute cooldown
Absorbs the next elemental magic spell cast by the mob, or the Red Mage or another party member, provided the spell was cast on or by the opponent to which the Red mage is engaged, and provided the element of the spell matches the current enspell element in effect on the Red Mage. The MP cost of the spell is used in conjunction with the weapon's attack power (and possibly other modifiers) to enhance the enspell damage for the remaining duration of the enspell.
The goal with the damage calculation would be ideally to double the damage possible through just the straight nuke damage, as enmity free enspell DOT. To reach this, you'd have to gear for accuracy and haste, your weapon attack power would matter, and you'd need to minimize cycle spells.
I agree with Seriha that minimizing cycling is an ideal way to bring RDMs to the front, but with the current direction of multi-purpose jobs the idea has been to require a stance to be chosen so that you can't be great at multiple things at once. BLU can be a good main healer but not if they're a great DD. Same with SCH. Good players can toggle well, but that would be the challenge here too.
Or, you could go the route mentioned above of making the next successful hit a spike damage loaded with the damage of the absorbed spell, modified by TP and other factors so the ideal again is spell damage x1.5-2 depending on your gear and skills.
Or! Let's say the default behavior of Runic is to enhance the enspell damage per strike for no extra enmity. But you could get an additional JA a couple levels later, "Runic Seal" that allowed you to channel the remaining power of the absorbed spell into additional weapon skill damage. That way if you reached a point where you need to stop meleeing to cure, enhance, enfeeble, you could still make use of the rest of the nuking power and your TP and gain enmity by using a magic infused WS. Ideally this would do less damage than if you were able to melee out the rest of the absorbed spell duration.
One neat thing about this would be the potential for another member to offer more damage to Runic. For example, through higher tier nukes or AM from BLM, SCH, SMN. The RDM could of course use Runic when soloing to enhance their own enspell via Tier IV's.
I also like that this could be used as a pseudo stun, but only for a single element family of spells you'd have to plan for in advance. It also minimizes the use of Runic as both a stun and melee damage enhancer because chances are you won't be meleeing against a mob with an enspell matching the element they like to cast.
My favorite thing is it would be awesome to randomly steal another party member's spell for my own damage by throwing up Runic while they're casting![]()