The key features to the sword was that it changes color multiple times in a day, and it represented joyousness. More of a mass media weapon than a slaying device.
For the color feature, I settled on using opal as a material source. Opal was reputed to be a gemstone that changes color, even when the owner dies. The change of light throughout the day would change the refracted light from the sword, so it explains the color-changing feature.
Was surprised to discover that gemstone blades do exist. Thus, reference.
Finding colors of opal that referenced joyousness wasn’t difficult; they do exhibit the colors of the rainbow.
The next step is ideation and form-building.
Did silhouettes for the pommel, guard and blade, and created options for the parts. Chose the ones I thought interesting if combined, and made a sword out of it.
Four hours work.