Consider subsuming Nourish to Kullervo. The added Viral AoE indirectly buffs the damage of all of his abilities by amplifying the Slash proc damage. It also adds Viral buff to your weapons, so it directly buffs the damage of Wrathful Advance. Lastly, the increased energy regeneration will make sure you can always cast Recompense, taking away any survivability issues.

Wrathful Advance works extremely well with daggers modded for high range because their heavy attack does a wide slash around you with guaranteed status effect followed by a stab that hits the intended target as well. It’s great with meta weapons like Nikanas and Tonfas too, of course.

Don’t be afraid of Recompense self damage. In worst case scenario, you’ll receive damage worth of a single dagger, this means that as long as there is at least a single enemy, you won’t be harmed and you will be healed and potentionally get Overguard too (depends on Ability Strength). Also, Overguard prevents knockdown, meaning you don’t need Primed Sure Footed or Handspring, and you can stack up to 5000 Overguard.

Collective Curse damage ignores the recipients defences. This means you can use the high damage you do to weaker enemies to significantly hurt stronger enemies. E.g.: Shoot a Butcher to take down a Bombard.

Collective Curse supports chaining, so damage through abilities like Discharge and weapons like Nukor or Cycron is extremely amplified by multiple chaining instances happening at the same time. The screen will be filled with crazy amount of number and everything will be dead.

Storm of Ukko provides very potent area denial thanks to stacking Slash status in numbers strong enough to kill most Steel Path enemies, but you can also use Collective Curse to spread out it’s full damage from the affected enemies to those outside of the dagger rain.

Use Transference when fighting Kullervo. It charges quickly during the fight and no matter how tough Kullervo may seem, even on Steel Path, our Warframes and weapons wipe the floor with him so quickly you could get all three stages of the fight done in a single Transference.