What is the best stage for farming materials to strengthen weapons?
Solution 1:
If memory serves, it would be red items. Just do the battles corresponding to the colour that you need (fire for red etc.) Also keep in mind that certain enemies drop certain resources. For example, sword users drop red stuff while cudgels drop yellow. Experimenting with this is what you'll want to do.
As for weapon style, anything will do but I recommend pole arms. I mainly used Diao Chan's whip with an immortal combo, but strategy aside you'll want to use a move set you like fighting with that has a large range.