Heavy Sword melee Veteran
 Veteran Build - Warhammer 40k: Darktide 

It's not the best build and can definitely be finished, but it's a very fun build for close combat veteran.

You can swap additional Toughness Boost for a Field Improvisation, but a think veteran doesn't have much ways to reduce toughness damage/replenish toughness quick , so I lean on Iron Will  and Voice of Command.

Only In Death Does Duty End is also optional. You can run all 3 toughness curio with revive speed instead. Personally I need more stamina for running and blocking.

Accatran MG Mk II Heavy Laspistol is great for sniping specials and put fire stacks on to a bosses (if we run out of Krak Grenade and can't kill it quick). Also it keeps my mobility. We absolutely need Infernus , but Concentrated Fire  is optional (Desperado will work fine too for our purposes. Dumdum isn't great, if we focus ourselves on melee). 

You can swap Laspistol for much heavier weapon, like M35 Magnacore Mk II Plasma Gun, or Locke Mk IIb Spearhead Boltgun, if you struggle with heavy armor. 

(If you choose Locke Mk IIb Spearhead Boltgun , be sure to grab One Motion instead of Longshot)

 Turtolsky Mk IX Heavy Sword (model is preferential. I choose IX for move set and for slightly better cleave) is a hidden gem of the veteran class. It is easy to use, and scale very high with Serrated Blade node. Deathblow  is mandatory. We need it for exceptional ability to strike two heads with FULL DAMAGE and, potentially, kill two Scab Rager with one motion (thanks to Precision Strikes and Exploit Weakness). For a second blessing I found best to use the Headtaker. It builds very well with Weapons Specialist and Trench Fighter Drill , but you can take any other, if you want. I run it with flak/maniacs and deal with Crusher by Kraks. 

For Scab Plasma Gunner and Scab Mauler aim for a shoulder (not the carapace helmet) with heavy attack or just spam light attack into body for bleed stacks (for some reason they take less damage to a head even with Precision Strikes).

For Crusher and groups of Bulwark (1 or 2 Bulwarks we can kill by sword mashing) we use Krak Grenade . Don't be afraid to spam it. We, literally, print new ones with Demolition Stockpile and Demolition Team .

For bosses again Kraks first then Burn/Bleed/*Sword_cutting*

For Captain's shields use light attack only (it will be quicker)

Other elits can be killed with one or two heavy attacks to a weak spot(HEAD).

Heavy sword can deal great damage to a carapace armour. So you can run it with carapace/flak or even carapace/+10% elite damage to specialize even more. We still need Kraks for a bosses.

Have fun!