Text of the card is unclear. Nothing stops a player from playing it on its own item. In multiplayer game it is unclear in whose marshalling point pile the card should be placed and to hand of which of opponents the item should be returned (even if the card is played on opponent's stored item). If target item is an opponent's item it presumably is returned to its owner hand and the card is placed in owner's marshalling point pile, but it is only guaranteed in two-player game (i.e. other possibilities do not exist), but text of Neither so Ancient Nor so Potent does not indicate so.Neither so Ancient Nor so Potent wrote:Playable on a stored item. Return item to opponent's hand (discard all attached cards). Place this card in opponent's marshalling point pile. Though it had been made in Imladris for Valandil, it was neither so ancient nor so potent as the one lost with King Isildur at the Gladden Fields.-Kuduk Lore
I propose the following erratum:
"Playable on an opponent's stored item. Return item to the opponent's hand (discard all attached cards). Place this card in the opponent's marshalling point pile. Though it had been made in Imladris for Valandil, it was neither so ancient nor so potent as the one lost with King Isildur at the Gladden Fields.-Kuduk Lore"