How can I make a system that allows players to create custom weapons while in the game?

[Khamai]

Pretend there is a GUI, it has 3 input boxes:

1.) Link to the weapon design as just a .PNG file

2.) Attack damage

3.) Attack speed

and let's assume hand positioning for said custom weapon has a default premade along with all other necessities. How would one make it so players can dynamically create weapons while being in-game?

And yes, you can ignore the things like sending requests to the weapon design link, I'm just curious how one would actually register this weapon while the game has already started.

[Draco18s]

The image wouldn't work, unless it was a url, as then other players wouldn't see it.

2 and 3 are controllable with vanilla NBT I think, but you can do it with capabilities too.