If all you are looking to do is copy some existing items in the game and modify their stats, etc., then you can find the weapons and armor in the root template menu, right mouse click on it and choose "Create new from selected...". After you give it a unique name you can edit that new root template item with the changes you want. Once you have a root template item, you can place it in the world somewhere, add it treasure tables, etc.
Yes, but my root template menu is empty. Do I need to enter sandbox?
In the resource manager if go to Shared->Assets->Items->Weapons, select WPN_Common_Sword_2H_A and choose "Create new from selected" it says "no available packages!"
Edit: In the sidebar it seems I can edit the weapon, there are lots of redudant options. The stats field opens the stats editor. But i get "This file cannot be edited, because it is not located in your current project" error in the stats editor.
Edit: I did create a package inside mymodname folder in the resource manager, now i got WPN_Common_Axe_1H_B_00 but it says it is a visual resource, is this is full weapon? In Shared->Assets->Items->Weapons, the type field says PhysicsResource/TextureResource etc. Somehow I think this is not the full weapon. Where do I start off from a simple axe/sword etc?
Edit: So, I clicked load in the root templates menu and now I think what you were saying works. Just need to figure out how to customize the weapon now.