
One is green quality the other is gold quality. Are you sure this is a nerf? Have you tried looking at a golden DWG item? You can check through reconstructing (but not actually pressing to confirm).
But yeah, that change from being damaged to getting the killing blow sucks but it's probably healthier for balance than getting 15 ultimate every time an enemy necromancer uses blastbones against you. Or something, idk.
This looks a bit like how.
https://elderscrollsonline.wiki.fextralife.com/Vicious+Serpent+Set
Require you to kill but
https://elderscrollsonline.wiki.fextralife.com/False+God's+Devotion+Set
Only demand that you hurt them so anything dying while you have AoE up will proc it.
And in an trial setting false god is much better just because of this while solo its no difference.