Taken from:
http://en.wikipedia.org/wiki/Final_F...Nintendo_DS%29
Sage: A hybrid capable of using every white, black, and summoning spell available. Although possessing fewer higher level MP, Sages have more MP for lower-level spells than other advanced class. Sages are unable to use the High Summon magic effects, but rather randomly switch between the white and black magic effects (similar to the Evoker).
Gone are the days when the Sage could cast the all mighty MegaFlare.
BTW: What happened to the Paladin class? Did the Dark Knight class replace it? I remember the Paladin could cast levels 1-3 white magic. Can the DK do the same?