Originally, 3.6e used Legacy Weapon as a term for weapons which had such a rich and significant history that they acquired (often legendary) powers on their own. With their original wielders now dead, retired, or otherwise out of the picture, players could discover these powerful weapons and, through side-quests, awaken them back to the power they had in their days of glory.

Now, this has been extended and named Legacy Items. Unlike Legacy Weapons, Legacy Items may be anything - a sword, brooch, or even a particularly preserved flower. All that is needed is for the item to have been actively involved in some great story. While the story need not be world-defining, the story itself needs to have power - a sort of rich umami of legend which gives the item a reason to hold the power it does.