I was never a fan of this whole “more heal when taking alot of damage during 5seconds” mechanic because i think its hard to balance, making the ability either too weak or too good. What if the way how this ability heals the death knight gets reworked?
For my first thought and example is:
Death strike
heals for 15% hp flat but you get a debuff for a certain duration where your next DS heals you less and/or costs more which can be stackable or something like that.
I dunno how this could affect blood dks in pve but maybe add a blood dk talent where their death strike turns into vampiric strike which makes death strike work like it is now.