Got this idea from Whisper's Variable Wispon Rifle and the different versions of the Monados and Aegis' Blades. I have the idea that the blade will change form with different Wisps powering it. One such idea is when the Spike Wisp is in, the Blade looks like the Ancient Bladesaw.
And when all Wisps are in for the Unlimited Colors: Final Color Blaster, it becomes the Final Color Slash. Think massive energy based blade or blade surrounded by a lot of energy and goes in for one giant slash.

Satoshi and the Prototype Wispon Blade