Idk, I play Flyff and their concept is this -
Armour Set +3 onwards glows. But the max (i.e. +12, glows super beautifully)
Weapon (glow effect depends on the attribute you upgrade it with, +12 glows better than +3)
I think this will encourage people to refine.. But of course from +5 onwards, there is a chance of breaking your weapon / armour. So you got to buy some MS items
Nevertheless, I thought this will be an improvement to the existing glow effects for unique sets and 4G equips.. Idk hahaha.