Lunar River [1]
There was only one thing Damien had never been able to overcome in the decade and a half since he began training.
It was his foundation.
From his days struggling in the dungeon to when he was a peak powerhouse in Hidden Death Valley, the problem followed him.
Damien grew extremely fast. He gained more and more power and achieved a feat nobody had ever achieved with his progression.
However, his growth waited for no man, including himself.
Vector Control was a great example.
When Damien reached 2nd class, he was too focused on escaping through the path Kurt Galloway left in the First Dungeon.
Afterwards on Apeiron, while he did use Vector Control, he never focused on its main ability, mainly using it to create plasma and boost his firepower.