One Piece weapons stuff I'd like to happen in the future ... may/not fit in the canon discussion.
1. Zoro will unite all three Kitetsu for one attack. They will then break. That's the curse -- united, they're utterly fragile. It will be hilarious.
2. Yamato will stop wielding the kanabo. It's a symbol of Kaido, and Yamato's disavowed Kaido as a parent. The club has to go.
3. Zoro will give Enma to Yamato, with Hiyori's full approval. Because if Yamato is to be like Oden, what better way than to carry one (maybe both?) of Oden's swords?
4. Zoro's only sword at the end of the series will be Wado Ichimonji, and he will be the greatest swordsman using only one sword. Because that's Kuina's will.