What about a SOAP?!
There will be an item in shop for some gigas and after using that item, your set will glow and shine like +5 parts. If you say that only +5 sets should have the shining effects, we could apply this to other sets like metorium, raid, survival, (E), etc. Using this item doesn't glow all of your sets which you equip, instead, each of the soap will only effect a particular set which you want when you use it with the soap, and no other set will have it other than that particular set. After soaping a set, the effect of the set will remain forever. Maybe you can soap a single part, however, the price of that soap may vary.