Instantiate prefab on inspector drop

Hello every one,

I have prefabs for items and weapons in my game, I have characters prefabs as well

at the start of the game there is a world creator script that has references to the needed prefabs to drop them on the map, when the player hits them he collects the items, the thing is at this point I have an instance for each of these items, they were instantiated by the world creator

however, if I wanted to modify the character inventory (weather the game was running or not), when I drop the prefab of items or weapons, it's not a new instance, it's the same instance shared whenever I drop this, which makes the instance variables shared like weapon health

how can I achieve both? I want to be able to customize how each character starts the game, or modify the players inventory at run time