Although the system had already determined the Hell Demon Sword to be Huang Yi's spoils, this Demon Sword was still the life-bound Divine Artifact of the King of Hell, who could exert significant influence over it.
If the King of Hell's power far surpassed Huang Yi's, he might even reclaim the Demon Sword, just as the Dark Demon Dragon Molei once reclaimed the Magic Dragon Wings from the Heavenly Demon.
But now, since the power difference between Huang Yi and the King of Hell is negligible, the King of Hell can only influence the Demon Sword, not seize it.
Huang Yi wanted to isolate the influence of the King of Hell, so he could only modify the Demon Sword as much as possible to greatly weaken its connection to the King of Hell.
The Slaughter Blade was his own Divine Artifact, and when its Artifact Spirit was devoured by the Demon Sword, a portion of the strength belonging solely to Huang Yi was embedded in the Demon Sword, giving him deeper control over it.
