Support Zealot - Combat Knife (Auric Maelstrom Ready) (Post UnL update Meta Build)
 Zealot Build - Warhammer 40k: Darktide 

Zealot Meta Build with Combat Knife (Post Lock and Loaded Update)
but as a Support Role
note I mostly play public Auric Maelstrom games, so I can't say how good this holds up against Solo Auric Maelstrom Missions.
 

Sing your way using your chorus of fortitude to grant Toughness and Damage Buff to your teammates! This is actually easier to play compared to my previous build, as you mainly take on the role of a support but help to secure a win for your team. You still get to join in occasional horde clear and boss battle, just you won't be as strong as you expect xD 

Personally I prefer Combat MK VI Knife as it is better at mixed hordes, with good horizontal attack pattern. Playing with Mk III for most of my gameplays, I feel that MK VI is much more useful (providing good mobility, dodge with good horde clear). Although Single Target Damage is reduced, my priority is staying alive and to get the team back up when suitable to revive. You can actually utilise special attack (which is the silly punch) followed by a light attack to quickly initiate Heavy Attack which is more effective against single target (e.g. boss, Crushers). Or you can mixed in with push (i.e. hold right click, hold left click) attack occasionally to get more single target attack.

Blades of Faith is really something that I can always rely on when there are specials, or even the occasional sniping of snipers (have to admit my aim is bad, but if you are pro you can easily take advantage of that).

Best picks for secondary weopon

1) Spearhead Boltgun with

a) For Bosses
Puncture + Shattering Impact

b) For Mixed Horde / Carapace e.g. Crushers
Pinning Fire + Fire Frenzy/Puncture

2) Zarona Revolver with Handcannon + Surgical (up to 100% crit chance)
Sniping Specials and Elites (penetrate through thick crowds)

This can be an alternate secondary weopon though not as good as Boltgun IMO.
Purgation Flamer is good for horde clearing or crowd control, I have tried so far with Inspiring Barrage and Blaze Away, but if certain auric map has little ammo pick up you can also choose Over Pressure and Fan the Flames (less damage but more Crowd Control)

Main thing about staying alive would be to avoid being trapped by specials (e.g. trapper, dogs) mostly with a good timed doge or push, and maintain your toughness with Chorus of Fortitude or Inspiring Barrage (if that’s one of your perks on the flamer). If all fails, when Until Death is activated get as much melee damage to close enemies or ranged damage if further from enemies (no need to kill them necessarily) and return back to your team, in which you will need to wait 2 mins before you are safe again. And please stick with your team and don't wonder off, you are not invulnerable, just able to deal a whole lot of damage to support your team!

Don't worry too much about curios you should pick what suits you best (so you don't have to follow exact). You can either pick for more health, more toughness, more stamina (if you find it hard to manage your stamina) and see which works for you! The essential ones you should bring is Gunner Resistance (hence in all my 3 slots)
 

An example gameplay of this build can be seen below