Suppose I have a weapon that does 1000 (black) damage and 1000 arcane damage, and I use it with a skill that says "Physical" in the skill tooltip. And I have some gears that says "Physical skills deal 20% more damage".
From the animation of how monsters died, I noticed dead monsters have a glow of arcane color on them, suggesting they were killed by an arcane damaging source, even though all my skills say Physical on them. This made me concern about whether "Physical skills deal 20% more damage" is actually useful.
I then did an experiment with a friend in the PvP (brawler) mode. My friend equipped an amulet that prevents arcane damage and heals herself instead. I then used that said physical skill with my arcane weapon on her - and she took some damage and healed some, suggesting my "physical" skill had a physical component and an arcane component.
Does anyone know how exactly the damage is calculated? Specifically, is that "physical skills deal 20% more damage" working to its maximum?