If I remeber correctly, in Dragonlance, casting a spell would take a lot out of you. I think it was like physical exercise. I also agree with Burthstone about using magic items though. He affects of said items should be weaker than magic from a natural sorcerer or magic user. 

My head hurts when magic is involved. xP You don't have to worry about magic from me though. My nation would still absolutely despise magic. There would be some underground alchemy guilds though. By the way, what's the status of gunpowder in this rp?