Inherent Weapon Mods

This is something that has been bugging me for a while. With the +15/20% while X mods on a Bow/Sword/Axe/Hammer, would this mean that had the +15/20% of the base damage or the actual damage done apon hit?

Say, axe for example; Damage 6-28 with a Damage +15% while Health is above 50% mod. Initially on hit it would be +0.9-4.2 damage, but would it remain this way, or say you hit executioners strike (assuming Axe Mastery is on 16) which brings it to 48-70 Damage with the +15% mod making it 55.2-80.5 damage?

I would say that it would not add to skills, and here is why (again I am just guessing here)

Exocutioners strike says - This axe attack deals + X more damage if it hits.

Meaning the damage your weapon did + X

I think this is the same for all skills.

Okay I tested it and managed to do 94 damage with executioners. I'm guessing it was a critical, but I don't have info on criticals. What I should be doing though if it does the damage on hit is 85.284 damage, assuming it hits for the full 32.16 damage with axe mastery at 16.