I heard that a rare ore, incendicite, was found in the Wetlands, in a cave northwest of Algaz Gate. Incendicite is volatile stuff and hard to use without blowing yourself up, but I'm sure if it's smelted the right way it could make cannon shells that pack a mighty punch!
Get me incendicite ore and I'll find someone brave enough to experiment with it.
Oh, and to extract that ore from a vein you'll need skill in mining. If you don't have it, then ... bring a friend who does to that cave!