The shader system should be converted to the same system that armor and weapon mods currently run on. When you get a shader for first time, it's permanently unlocked and in your inventory, When you want to apply it, you just pay a small amount of glimmer. I don't think anyone enjoys the laborious task of deleting huge stacks of shaders. This has been a problem since early D2, and I think the new mod system is a good template to fix it.