DMG drop while attacking DH GOD set

DH GOD set ethereal 2h 8mil damage, once i start attacking my damage drops to 5mil. Not sure if this is a bug or an item that might be doing it. Elusive ring/Grander/Hellfire Amulet. Buriza/Sin (legendary), Hunter’s/2 pc Aughild’s. Dawn/Depth/Obsidian cubed. This only happens with this setup. When i switch to dual weld, damage is around 3mil and only ups with pylons and shrines.

I’m going to take a guess that your ethereal rolled with this passive…

…and whilst you’re not attacking your CHC rises to 100% (vastly increasing your sheet damage number) and as soon as you start attacking mobs your CHC resets to its actual base value, lowering your sheet damage value to its actual level.