Remember final fantasy XIII versus? Probably not, but
this trailer boasted some pretty spectacular looking weapon concepts. Instead of the main character having his weapons on him, he is able to summon them as spectral swords or as physical weapons bound to the laws of physics. He has a massive arsenal literally at his fingertips that serve as shields in their spectral form, and teleportation devices when he throws them. Since it's part of the Nova Chrystalia arc, it's no doubt made possible through that world's crystal energy.
I know, I know, the whole magic thing is still in the air as to how it works, but this may be an interesting use for... Spirit gems, I guess. Since the spirit world is 'accessible' through them, perhaps access to the spirit world would allow you to soul bind weapons you forge there to you such that you can latently control them and 'use' them in the real world. However, it does raise the question of how, or rather, if, they would be exclusive to each player, and how they may work. I have some theories of my own, but for now I'll leave you at that.
