Alt skill effects that exist but aren't available

Hello, i was wondering why there are Alt skill effects that exist, but are not available for purchase?
For example, i recall seeing a blue rain of arrows, and an alternate color for spectral throw from a boss(an invasion boss i think). I thought they looked so cool, but they aren't available for purchase. If they already exist, why not add them to the shop?

I agree with you. They should bring back all alt. art and items as skin trans you can buy in M. Why wipe them out of existence?

right? bump :D

Maybe they wait to see how people recieve them on enemies first to get an idea of what price to put on them.

bump!