Can we create new weapons thanks to the unreal editor ?
You cannot create new weapons yet in UEFN, but you can directly damage a player using the Damage function.
The source files for weapons aren’t able to be copied, and Epic doesn’t plan to release official support for custom weapons yet, but it is… kinda possible. It’s very limited, but using the signal triggers, it is somewhat possible, but it’s very elementary and not very diverse.