Get more weapons in the shop
Getting new weapons is not incredibly easy, but you will receive a few free ones as rewards for progressing through the game, usually as star level rewards or from the various crates that you can purchase from the shop.
However, you should always keep an eye on the shop itself because at the bottom you will have a selection of weapons that you can purchase directly. These are pretty expensive for sure, but if you need a particular weapon to complete a fusion, then it could be money well spent.
We don’t recommend constantly buying weapons this way, but it helps a lot if you need a particular one, so check out the store constantly!