Arbites Combat Ax + Combat SG (Havoc Ready)
 Arbites Build - Warhammer 40k: Darktide 

This build can clear H40 with... well, about as much difficulty as Arbites ever has. But, quite frankly, most of the testing with this build was done in Auric Malestrom. Still, the sheer single target pocket ICBM that is Decimator will hit two-shot (if not one-shot) breakpoints on Crushers, Reapers, and Bulwarks. With buffs active, I've found that the Combat Axe scarcely fails to one-tap Maulers and Muties. Ragers are somewhat of a problem with this build, but... just don't get hit and chop 'em down.

Note: Damage as the dump stat because it SHOULD be. Damage rarely helps you reach any breakpoints. In general, the Damage stat on its own gives... diminishing returns past 60 or 70. Mobility should never be thrown away without any thought, unless you're using something like the Dueling Sword on Psyker (the excessive dodge distance can be more of a curse than a blessing). If you like bullet sliding, slide dodging, sprinting, and just generally not getting hit by shit and chewed up, having more mobility goes quite a ways. This is why Ogryn was objectively the worst class, even below Psyker, for so long.

As for the shotgun, Maniac and Unarmoured help this thing reach breakpoints specifically against Flamers and Dreg Gunners. Manstopper helps stagger Reapers. DO NOT use this thing to kill Muties (Mutants literally take increased damage from melee), they'll sooner rush you before you can get the kill off and you'll need to engage them in melee anyway. Pop a slug in to counter-snipe Snipers, execute Flamers before they're in flamethrower range, and use your basic buckshot to deal with shooters or to suppress and/or stagger them. Don't expect to cut Reapers in half with one shot like with the Arbites shotgun, it still takes SOME effort. The Agripinaa rewards having good aim, but if you aren't as confident, switching to the duckbill (Zarona Mk VI Combat Shotgun) variant will help with crowd control. (If you're using the Zarona, use Scattershot and Man-Stopper).

Combat Axe can be substituted for the Atrox Mk VII Tactical Axe if you would prefer more mobility and CC capabilities. Or if you simply like having infinite dodges, I guess. Lastly, Break the Line should be used almost immediately off cooldown. However, disrupting enemy lines doesn't do much for you if you're dying anyway. If this is the case, use the Nuncio-Aquila and both its child talents. The remaining talent point should go into your Keystone. Alternatively, because Arbites's keystones (in relation to this build) are kind of ass, you can go keystoneless to pick up some more heavy hitter nodes, such as Prosecution Blow, Rebreather/True Grit, etc...

I highly advise AGAINST keeping the dog in this build. The Arbites Grenade provides unparalleled value, and the 60s regen (not to mention the +1...) cannot be overstated in its usefulness. This is why Arbites is stealing Vet's lunch... Besides, we've survived this long without the dog's help. If you still are having issues with disablers, I suggest installing the following:

https://www.nexusmods.com/warhammer40kdarktide/mods/384

https://www.nexusmods.com/warhammer40kdarktide/mods/268

No skin off your back. If the sound queues worked 100% of the time and we could perfect react to them 100% of the time, then yes, this would be quite a crutch. But they don't. So it's not.