The Lord of Glory was a true god, however, as humans went on campaigns to conquer planes and slaughter adherents, even invading the realms of the gods, most powerful gods fell one after another. The Lord of Glory was but a lesser god of grade-15.
The Magical Element Tower that the grandmaster had crafted for Saleen had been a grade-16 equipment even at the very beginning. The dimension stones within the tower were all upgraded to grade-18 after it was modified by Gaine.
Regardless of how powerful a godly item of grade-15 was, in Van Gogh's hand, it would have performed as grade-10 at most. Such was the limitations imposed by the rules. Any common person would have been able to go on a killing spree and fell powerful ones easily otherwise, and that would have been a joke in itself.