Wasteland 2 Directors Cut seems be without much modding support these days, the following link gives some some information on how to mod WL2DC, but is very limited in details.

https://wasteland2.inxile-entertainment.com/game/modding/introduction

After much trial and error i got it working, basically if you have installed your game in say "D:\games\Wasteland-2-DC\"  then for modding your game must have the following Directory Structure

D:\Games\Wasteland2-DC\WL2_Data\Mods\Import
..........................................................\Arizona
.........................................................\DropSet
.........................................................\ItemTemplate
.........................................................................\ItemTemplate_Equipment
......................................................................................................\ItemTemplate_Armor
......................................................................................................\ItemTemplate_Weapon
................................................................................................................................\ItemTemplate_WeaponRanged
................................................................................................................................................................\ItemTemplate_WeaponEnergy
........................................................\JournalEntryTemplate
........................................................\MobTemplate
........................................................\StatusEffect
........................................................\VendorSet

if you want to only mod weapons you put the ".mson" file in the corresponding folder*(ItemTemplate_WeaponRanged). Note Energy Weapons have there own sub-folder. Examples of files are on the web site

Untested whether you need to start a new game or not. hopefully someone will do that for me?
Also Check out
Chuck's Cheating Wasteland 2 Starter Mod
Nice little mod, a little OP for my tastes though.
Disclaimer
I don't own Wasteland 2 , wish i did though.....sigh.
Copyright
Seriously ...... do what ever you want with it .