https://www.grimtools.com/calc/RVvqmdk2
As I was following this build I was wondering HOW THE HELL DID THIS GUY use to wield two weapons while it doesn’t work on mine? I don’t see any items that has a passive to use dual wield…! How the hell did it work?
Its the gun
I don’t see that on mine, maybe I need an update.
Not all guns allow that. Only few ones.
The darkblaze pistol allows for DW.
P.S. I made some changes to the link you provided just because I’m nosy. 
Explanation is as such:
i. 1 point in vulnerbility for more DA shred.
ii. 6 points in searing light for 30% fumble
iii. I hate BWC personally in this build, simply because the AoE is too damn small for RR. IMO, you’re better off swapping abominable might and BWC for manticore.
iv. I would then place the saved points into wasting for OA shred.
This is your build!?
-> Update solves the issue.
-> I’ll take note of your advice, thanks! 