Help me understand the Harmony of Ebewaka Helm

As in the title. I’m doing the Quill Villey build from IcyVeins and just don’t understand how it works. The build description says more or less “due to Harmony of Ebewaka the more armour you have the more damage you do”. I have the helm, the build seams powerful, but still reading through the helm description I don’t see how armour can affect damage. Please help me understand