The so-called Priest is one wholly devoted to serving a Deity.
The greater the devotion, the stronger the response one receives.
Bartle, as the first Priest of the Mercury Avatar, almost had all the attention from the Evil Silver Gradient.
Hence, although his own Power had not reached the Legendary Realm, he could use a very powerful Divine Art exclusive to priests—Divine Intervention.
With a mortal's body, borrowing the power of a Deity.
Back then, Supreme Decree James Watson used Divine Intervention to draw the gaze of the Lord of the Dawn, such that even the Headless Knight Gareth had to temporarily avoid confrontation.
It was with this Divine Art that Bartle summoned the projection of the Evil Silver Gradient.
