So what would a golden nirnhoned mace's execution damage would be?
Let's say, 5k weapon damage on an enemy that is at:
40% health
30% health
And 15% health?
Depends on way to many factors: pen, buffs, debuffs, etc. Expecting an answer to such general question is like throwing a *** in a gay club and expecting to get ***. Not gonna happen boi.
The scaling for the execute on the skill executioner, which I believe you are asking about, is liner. Meaning that starting at 49% health, you get 7% more damage of the Tooltip, 25% you get you get 175%, 1% you get the full 350% extra damage.