Which is stronger, Death Harbingers/Banshees or Death Knights?

That's exactly the point – introducing dark energy sharply limited the number of troops that could be raised, especially in the early weeks. And, despite the ability to raise everyone, it significantly weakened the Necropolis faction.

Yes, there were times when they could easily defeat everyone. In my opinion, it would have been better not to introduce dark energy, although it did weaken the Necropolis. But what can you do with 500-600 dark energy? Raise a couple of dragons? Or 9 Liches? It doesn't seem to help much. I won with an advantage thanks to those 9 Liches :D. No other way :D.