D&D: Conservators of Ring World
Traditional magic Items as presented int the DMG tend to function but in a reduced capacity. Essentially all magical items will were out of use or only function for so much time on a given day.
Mana Stones Change this. A Mana Stone carries its own charge that can be used to power ma magical item. a +1 sword with out a man stone may only glow with brilliance for a short time each day as the enchantment fades. If the Same sword is bonded to a mana stone it will continue to radiate magical power until the mana stone is removed or suppressed.