Originally Posted by
Zeromus_X ^ Conjurers can use the lower level healing and support spells, and Summoners use the high level summon attacks. Sages can't use the high level summon attacks.
This is true in the DS version. If you're playing the NES version, the Sages use the high level summon attack. Whether Ifrit uses the healing move or the torching move is based on your luck, AFAIK.