He had been keeping it a secret all this time.
Upon awakening to the new era with the help of Rex, he meditated and expanded his senses and found that his brothers—or even the other strong entities from the empire were nowhere to be sensed, the Executor was isolated in a time when those he knew were not around.
Realizing this, he instantly attempted to track down the Supremacy of One.
A treasure that unlocks the power of the strongest weapon—forged by the Supreme One.
It turns out to be in the possession of a civilian within the borders of the Human Territory.
Only those who are in the possession of the Supremacy of One could wield it.
The Executor spent every single second of his waking moment imprinting his aura inside the Supremacy of One, and he did it discreetly when nobody was looking. He took extreme care of this gem as if it were his own life or even offspring.
Back in the past, he could only view it from a distance.