I apologize for the poor explanation, it was an afterthought on my part. I'm working on new features/reworks and I'll be sure to improve tutorials/explanations. But to explain it as best I can; each mission randomly generates a monster to take down. Each monster has set resistances/weaknesses to each weapon type. You need to select at least 1 weapon type and have enough Gold to cover the cost of the mission to start it. Starting a mission will lock out any used weapon types for every other mission (you can unlock a 2nd use for each weapon type by prestiging further). If you only have 1 mission at the start then there is no downside to using all weapon types for 1 mission. Enchanting your weapons will increase your success chance and always be available for every mission but will increase the cost of the mission. I hope this helps!