Storing and using weapons and objects

Good afternoon, I'm planning a system that I use, but I'm with some questions... I am creating a game where it will have a system to store weapons and objects, as in the main RPG's, where the user can pick up a weapon or object from the floor and use. I've done the whole system to pick up the item, hold the hand of the player and all that, my question is, will bring various items and weapons to the game that will not be visible in the scene, and will be acquired in some other way (purchase, crafting , among others). I wonder how I can "store" all these objects in the game, to be initialized later... I must use instantiate when the object is obtained? Also, as I will add many objects, I must enter the unity and manually add each object, or is there some way to make an external database, to facilitate the future?

Thank you!