ZeCrit
 Zealot Build - Warhammer 40k: Darktide 

ZeCrit Zealot is all about more crits for more damage, and tons of TDR

Relic Blade (both marks are great) or Evisc XV 

Perks:

• Unyielding - due to prevelance of Monstrosities in Havoc, this is always a solid option for any melee weapon that does good boss damage.
• Elite - Helps to kill ragers and Melee Ogryn - can be replaced by Carapace.

Blessings:

• Cranial Grounding - 
• Rampage - More power is more fun. Since Light attacks have a cap of 4 enemies hit, cleave options are not ideal - Perfect Strike is okay as it will let you cleave through Bulwark shields and Crushers to clear enemies around them.
   

Revolver - A solid ranged weapon, with very fast swap speeds and fast special kill time.

Perks:

• Flak - Assists with 
• Maniac - Helps to kill Mutants, not necessary for headshot crits, but if you don't get crits it will assist in 2 shot breakpoints. Can replaced with Carapace.

Blessings:

• Surgical - Grants Critical strike rapidly, once Blazing Piety is stacked you only need 2-3 surgical stacks before your crit hits are very consistent.
• Crucian Roulette - More critical strike - crits are very necessary on this gun for it to deal damage.

Duellist, Second Wind, Blood Redemption, and Scourge are all interchangeable - Blood Redemption only needs 3 kills to match each proc of Second Wind so it is better in melee generally, but the latter can proc off many ranged attacks.
I generally find (while Relic sword is powered up particularly) that any crits you get will just kill everything you hit, so Scourge can go long periods of time without getting a single stack.

The grey 15 toughness node can also be used to get Second wind  but remember that is a 13% increase in total toughness, which also increases all toughness regen options by that much as well.