Damien was in the midst of a swarm of energy.
When the storm parted, the Dark God's shadowy form glitched and turned into a horde of locusts that swarmed him.
Each and every locust was filled with the energy of Existence.
It would be fine if it was only a single energy, but that was not this vein of Existence was manifested in countless different forms.
The Dark God had traversed so many cosmos and seen so many different energy forms with different laws that he was able to create something like this.
Damien was using a sword. He could act against the storm because it was a large and formless entity. Each of its attacks was relatively independent, and against concepts, just concepts were enough.
This swarm was filled with millions of physical creatures. Each physical creature had its own concept within. Damien's sword was fast and precise. It was able to make wide-range attacks as well, but he couldn't just blindly swing it.