Damage increased augmentation in skill wheel - what are the values?

Question

We have an enigmatic description of skill damage augmentation "damage increased". But what does it mean? What is the percentage damage increase for:

a) groundshaker

b) fierce berserk

Answer 1

Polish youtuber/streamer Maxigashi did some tests on Fierce Berserk and the conclusion was that it was a ~10% upgrade

Here's the link to video:

https://www.youtube.com/watch?v=_6j9EH3R5OE