Once the assimilation was completed, Shawn's fighting strength would inevitably advance by leaps and bounds.
It would be illogical for them not grow stronger once fused...
Moreover, that Evil Dragon Eye was a True Spirit Magic Tool made out of the eyeball of an Abyssal Evil Dragon.
In the legends, the Abyssal Evil Dragons were the most loyal servants of the Ancient Gods during the Gold Era. They had endless power and could fight against Chromatic Dragons. But after the Ancient Gods fell, the Abyssal Evil Dragons fell into the Abyss.
Anyone with a bit of knowledge about the Abyss knew that the Abyssal Evil Dragons were overlord-type existences in the Abyss. They didn't have a set residence and would only drift to various corners of the Abyss. But a battle would immediately start if an Abyssal Evil Dragon entered an Abyssal Plane occupied by a Great Overlord.
All Abyssal Evil Dragons had the power to contend against Great Overlords.