CQC Vet (Knife + DB)
 Veteran Build - Warhammer 40k: Darktide 

I made this build to try to use the DB on Vet. Originally it was a bit different, but through trial and error and some feedback from others, I've changed it, and it may match the original Weapon Spec DB build, I'm not sure. 

It's a little hard to fit into havoc comps because you kind of need someone with good horde clear, and if you don't have that then you need to bring shredders instead and swap a few talents around (I'd take Grenade Tinkerer and Marksman then, so you have some on demand boss burst, though you could keep rending strikes for better shredders I suppose). You also ideally have someone with a good anti-ranged ranged weapon (not the DB), because the DB just isn't that effective at long distances. Which makes the build a little awkward since most people expect Vets to kind of handle that, the same way they expect most psykers to have inferno and ogryns to have taunt. Yes, you can still kill a sniper from a mile away with a couple of shots, or a bleed, and yes, with the knife you can zoom around killing ranged. But if you get in too deep, over-extend, or are unlucky and have some gunners spawn behind you, you better pray to the emperor. 

And you're incentivized to go run into ranged to kill them, which routinely puts you in risky situations.

That said, it's fun as hell. A lot easier to get away with combat knife shenanigans in aurics due to full toughness and less incoming ranged damage. And in havocs, if you're teammates have good teamwork and you can fit into the comp as an anti-elite killer with decent horde clear, and decent boss damage, then it's not bad. 

Kind of a high skill build IMO though (It's taken a lot of practice for me).