William himself was unable to enhance his own abilities, but thousands of years ago, during the era when the gods still existed, he had created some methods to enhance abilities through his interactions with the gods.
Just like the method he taught Alice to enhance her abilities.
In addition to this, William had also created numerous techniques shrouded in mystery.
For instance, Zeus had once used William's creation, the "Olympian Thunder Technique," to enhance his control over thunder and lightning, ultimately establishing Olympus and becoming the chief god in mythology.
Another equally famous technique was the "Ninefold Arcane Art."
The way that girl earlier channeled her energy was clearly the method William had taught Artemis. William had only taught this technique to her and was certain that, apart from her, no third person knew this technique.
But wasn't Evelyn supposed to be Artemis, who had reincarnated thousands of years ago?