Slight spoilers, but according to the Astrologian Questline, Geomancers rely on the powers of Earth, Wind, and Water. Astrologians and Geomancers are supposed to compliment each other. Astrologians read the stars for the future, and act mostly as observers or participants. Geomancers use the elements around them to predict the future and play an active role in whether or not it comes to be. The Geomancer NPC also takes a LONG time to perform his rituals.


Quote Originally Posted by Maku View Post
/snip
Given that the only iteration we've seen of GEO seems far more similar to an Exorcist class, that may be why, but then, since when has an NPC accurately described a jobs function in game? I believe when we first saw whats-her-face using a magical rapier (basically revealing Red Mage) she was still using the PLD moveset.