Black Mage would work perfectly if you take 8bit Theatre's personification of him. He'd essentially be Wario + Knives + Spells. A good combination. We could even give him a nice hat.
If we took a pure character, though, I'd like to see one of the more major players from the universe. Not Cloud or Sephiroth. Why? Because they are sissy pansy babies, that's why. Give me a true hardass like Cecil, Sabin, or Cyan. Locke would work as well, as would Kain. Rydia would be a nice female compliment. Terra would work...if she gets Magitek armor. The most obvious is a Moogle, or Moogle + Chocobo combination. Sadly, as much as I hate Cloud and Sephidork, I know those two have the highest chance of appearing (outside of Sora).
Wolfkin's post mentioning Soul Calibur makes me wonder if he saw the recent announcement concerning that series, and how the pure blood that flows in its veins has been horribly disturbed.