All I know is that if you "loot" the item from a creature it will be visible under that creature's Bestiary information once you have it fully unlocked. My question is if any research has been done to what actually triggers the unlock? Is it the act of killing the creature and it dropping the item or physically looting it from the body?
For example what if there are 2 players who are not in a party. Player A kills the creature and it drops a very rare item. Player B waits 10 seconds until they can loot the item from the corpse. Who gets the item unlocked in the Bestiary loot table?