Borderlands 2 Quest Reward Items can only be farmed by Read-Only farming.
How to Read-Only farm:
- Go to the location where you hand in the quest.
- Save the game by toggling your Badass Rank on/off.
- Then go into the file explorer on your computer. Go to the file path:
C:\Users\NAME\Documents\My Games\Borderlands 2\WillowGame\SaveData
- Go to your most recent Save File (.sav) and:
right-click → properties
- Under General tick the Read-only box.
- Back in-game and hand in the quest.
- Exit to the main menu, then back into the game.
- Now you will be able to hand in the quest again.
Store the items in Claptrap's Secret Stash.
This way you can get the quest reward items multiple times since they are saved on a different SaveFile.