Power Shroud Zealot (Relic Blade, Boltgun, Blades, Shroud)
 Zealot Build - Warhammer 40k: Darktide 

No idea why I created this build. I thought may be it will be fun to have a Zealot build that can both sneak AND punch hard. Thing is, it kinda works, I've been consistently surviving up to Auric's Maelstorms and Havoc's 20s for several days with it, good enough for me. Still trying to figure out why would it need stealth if it can just punch everything to death :D Sometimes it comes in handy, and those backstabs at bosses are still kinda sweet. Will keep experimenting with it.

Few tips:

1. Drop HP to about 2 wounds asap to achieve optimal performance
2. Use Shroud to get behind some ogryns train and start hitting; first hit to the back (from stealth) usually kills an ogryn even with uncharged sword
3.  Also use Shroud when surrounded and overwhelmed, to restore 50% of your toughness, drop agro and get backstab dmg and toughness dmg resist boosts for 5-8s - then finish them off
4. Use Boltgun sparingly, I mostly use it for bosses and when ogryns trains become extra ridiculous; also sometimes when extra hoard clearing is urgently required, or there are a lot of shooters we can't reach atm; most specialists can be killed with Blades and they are much faster
5. Beacon of Purity will prevent those embarrassing deaths from corruption eating away your HP through toughness
6. Yes, it's not a mistake - I dump Damage to 60% on the sword, to get 80% Mobility instead; it just felt right to give some extra speed to a (still) stealth build; my tests have shown that it doesn't seem like Damage and Power Output (which is damage that is dealt with powered-up sword, thus the most relevant to you) are interconnected, and thus base Damage is of less importance here than it normally would