Warp Entity
 Psyker Build - Warhammer 40k: Darktide 

Run Obscurus for the combination of infinite dodges, Slaughterer (very consistent power buff) and Uncanny (Very consistent armor debuff). Dueling swords lack slaughterer and lack wide attack patterns. Obscurus combines all the best traits into one sword. Wide attacks for horde clear, strikedowns for armor, infinite dodge to maneuver through tough hordes.

Now, both Surge and Obscurus have poor mobility modifiers (Sprint Bonus and Dodge distance). Disrupt Destiny will fix this weakness while providing strong damage buffs for killing marked targets. Marked targets are extremely easy to kill with Surge and Creeping Flames as the majority of your targets will be Scab/Moebian Shooters and Bruisers. 

Surge is phenomenal for stunlocking armored targets (Crushers/Maulers) as well and quickly eliminating gunner groups without needing ammo pickups. (A big pain point for Disrupt Destiny while running guns). 

It's worth noting that Staff Bound Smite (Surge) lacks the ability to hit weakspots so you will sacrifice DD's weakspot bonus while using Surge, but you will hit plenty of weakspots with Obscurus and Surge has a very high crit chance modifier so you will still benefit noticeably from DD while using Surge.