Zealous Vet
 Veteran Build - Warhammer 40k: Darktide 

Veteran for chorus relic blade zealots looking for a change, and players who like to go fast. Generic elite killer with melee bite.

Lethal Proximity bolt pistol for enhanced frags (the increased explosion radius affects frags), better shooter suppression. Puncture is generally extremely good and stacks bleed with frags, but Deadly Accurate could be funny since you'll have 100% crit chance with 3+stacks of ranged specialist. Haven't tested if it hits any notable breakpoints or does appreciable extra boss damage though. +Unyielding helps killing reapers (and sometimes emergency boss contributions), +Flak helps with killing scab gunners.

Focus Target! is probably better than Weapons Specialist for havoc if you're the only vet, esp if your team lacks burst boss damage, but the lack of on-demand crits will hurt elite/special hunting abilities. As built this would be a great second vet.

If you keep On Your Toes , might be worth swapping the health curio for more toughness - should be easier to maintain Iron Will. In that case, maybe take Sniper Resist in place of Corruption resist to prevent instagibbing. I'm more comfortable having the extra health cushion but up to personal preference

Power Falchion Notes

• You can dump either mobility or heat management. Dumping heat management instead of mobility is great fun but requires a bit more intentional activation and deactivation. Note that heat buildup is unchanged from 60-80%, only cooldown speed is slowed. Also note that with Agile Engagement you can clear chaff pretty well even deactivated.
• Blessings are somewhat flexible. Cranial Grounding is probably the most solid all around. Heatsink helps with uptime and is probably the best choice if you dump heat management, since it will also apply when deactivated. Wrath seems to be meta but it doesn't feel strictly necessary to me. Energy Leakage helps with single target and also applies while deactivated. Overload technically makes your cooldown faster from the max when triggered, but at the expense of not having the flexibility to reactivate for a few seconds.
• Perks are also somewhat flexible. I always take +Carapace for the capacity to quickly kill crushers and maulers. Second perk is a tossup between +Maniac and +Flak - better performance against a) dreg ragers and muties or b) scab ragers, dreg bruisers, and scab captains.
• PF functions similarly to relic blade - activating and deactivating windows count as blocking, and it's always quicker to deactivate by swapping weapons
•  Both marks feel equally usable / good but I'm not an expert. Meta seems to favors Lawbringer Mk IIb Power Falchion but I feel comfier with the Aridin Mk I Power Falchion - its CC doesn't require block cancelling and all hits are extremely horizontal so it's easier to proc weakspot blessings imo. Single-target rotation feels a bit slower though

• Crowd control rotations

  *  Lawbringer Mk IIb 

    - H1 -> L2 -> L3 -> block cancel -> H1 ...

    - H1 -> L2 -> H1...

    - Push attack -> L2 -> L3 -> block cancel

  * Aridin Mk I

    - L1 -> L2 -> H3 -> L2 -> H3 ...

    - Push -> L2 -> H3 ...

• Single target rotations

  * Lawbringer

    - L1 -> H2 -> L1...

  * Aridin

    - Push attack -> L3 ...

    - H1 -> H2 -> L3 -> H1...

    - For Lighter targets:  L1 -> H2 -> L3 -> L1/H1 ...

Alternative talent choices

• I prefer Close Quarters Killzone over Reciprocity on this build
  • Frag damage gets buffed by CQK! If you're within 12.5m, the full 15% extra damage is applied to both the initial explosion and to the bleed DoT!
  • Weapons specialist provides guaranteed ranged crit generation, so extra crit chance isn't as crucial for specialist removal
  • Reciprocity doesn't always have great uptime (I typically have ~15-25% with an average of ~2 stacks or less)
  • This build is pretty angry and will probably spend most of its time chopping stuff up at shorter ranges
• Most of these nodes feel pretty optimal. Grenadier is good for maximum fragging but it's the least essential imo.
• Can swap something for Out for Blood for greater toughness sustain, Born Leader for stronger shouts, or Serrated Blade for even stronger melee performance
• Goofy Zone
  • Swap Grenadier and the On Your Toes keystone mod for the left bottom side tree node Precision Strikes. Expensive but lets you hit some breakpoints without crits if you frequently find yourself without stacks
    • Losing On Your Toes means less opportunity to keep your toughness topped off to keep Iron Will active, so it's probably worse for havocs
    • Another variation if you want to knifemax instead of power falchion: remove Only In Death Does Duty End and replace it with Serrated Blade . probably not suitable for havoc but it's a ton of fun for anything less serious. 
  • Swap the very bottom middle +25 toughness node for the adjacent Rending Strikes to lean further into glass cannon / make frags marginally spicier