His tankiest sword bearer
 Zealot Build - Warhammer 40k: Darktide 

Bleed for the Emperor and Faith's Fortitude together allow you to survive a Crusher overhead attack without triggering Until Death. 
More HP on curios will allow you to take some chip damage before that and still survive an overhead. 
With so much HP, we also take Restoring Faith as it is an effective HP multiplier, and it also synergizes with Bleed for the Emperor a lot, since it can bring you just back up over a wound threshold after being hit for reduced damage, so you can reduce the damage of another hit.
With this build you are almost as tough as an Ogryn as long as you are landing crits to trigger Enduring Faith. 
You are also multiplying the team's damage to any target you crit thanks to the combo of Scourge and Blinded by Blood. 
+ your Chorus of Spiritual Fortitude will increase the team's damage even more.

I prefer the Munitorum Mk II Relic Blade because it has faster attacks and still has access to all the combos you need for each situation.

In particular, the first 2 light attacks are quick and easy overhead attacks for single target DPS, with no recovery clunk in between block cancels. No need to do any clunky heavy attacks for single target DPS this way. Also no need to do any Heavy attacks against hordes due to the Push Attack into Light attack combo, though you will run out of stamina if you block a hit after a few of those combos. 
That's why I would rather have Retaliatory Defence instead of Punish Impiety.

The blessings chosen are for maximum duration of special empowered attacks, just make sure you turn it off before overheating so that you don't get locked out, this way you can still turn it back on while it's cooling if you really have to.

Horde clear options:
Push Attack > Light > Repeat
Push Attack > Light > Heavy 2 > Light > [Heavy 2 > Light] => endless combo
Push Attack > Heavy 1 > Heavy 2 > Light > [Heavy 2 > Light] => endless combo
Heavy 1 > Heavy 2 > Light > [Heavy 2 > Light] => endless combo

Single target options:
Light 1 > Light 2 > Block Cancel > Repeat
Light 1 > Heavy > [Light 1 > Heavy] => endless combo

The Laspistol can kill 3 Reapers before having to reload, with high accuracy at any range, and burn Monsters for constant DPS before engaging in melee.