And no, the mages do not hurl fireballs willy-nilly. A fireball requires manipulation of fire into a spherical form, air into a method of propulsion and earth into an extended-burn fuel. This would count as a very high-level spell. They manipulate elements subtly, like changing the course of a water, inciting a strong breeze, making fire jump, cracking a clay vase, etc. It's nothing over the top. Magic is not conclusively proven to exist in this setting. The mages are like weird scientists who most people think are crazy. No one is sure if they actually DO anything (except the FateGuard of course).
The arcane and divine magic in this roleplay is a force of chance and slightness. It gives you a temporary upper hand. It cause coincidences. It plays on superstition and human faith. It is not D&D.