Wouldn't it be easier to give a character a property that you can set if/when they hold/wear the object? Seems quite an obscure thing to put in as a main restriction.
Obscure - maybe.
However if you are checking more than one object the number of properties to check could dramatically increase.
Also, this may be taken care of already, if the PC changes character this could then be used to check if the PCs previous character has held or worn items.
New Restriction - Obj Must Have Been Held/Worn by Character
