Thread necromancy, but I wanted to get back to another thing related to this topic.
Can anyone explain the mythological origins of the Diamond Bell in FF?
I don't know about the diamond bell itself (it's usually the weakest one, even if it's made of diamond), but I think that the bells themselves are some sort of reference to earthquakes, which fit rather nice to Geomancers, among other things.
The waves produced by the biggest earthquakes actually bounce inside our planet, and produces a very low "ring", just like a bell. So the bell would represent the planet while the clapper inside is the waves, and the Geomancer moving it can be seen as they controlling the power of the planet, which is their ability most of the time.
Also I remember reading that geomancers in japan are "Feng Shui
Knights" which is also connected to things like geography; and bells are used to stimulate positive energy too, I think.