I believe...
...the only ways items are created are by 'finding' them hunting undead/monster bosses, interacting with a sage, and manually by GMs/admins. Creation of new unique items is regulated by density of current existing unique items on the island.
...the only ways lost items are rediscovered, in order from highest possible chance to lowest possible chance, are by investigating, gathering, looting, advy/priest travel (other character types travelling is intended but unimplemented), and foraging battlefield. Regardless of difference in successful-find chances, the chances are all quite slim.