No Underestimation.

The advantage of numbers is clearly on the side of world gods, but the advantage of power is not. World gods can avoid the world enders for now, but soon, the world enders will become too many to avoid. After all, world enders never die, while world gods run out of realm hearts to build worlds. 

Then there is Aeternus who has a power similar to those of world enders. From the information he has, he knows that Aeternus is not as dangerous as the first sage will have everyone to believe. He knows that Aeternus can't control that power yet.

But he also knows that Aeternus can become dangerous if he is pushed to the limit enough. He might just lose his sanity and succumb to the corrosion down below. So while Aeternus is currently of moderate danger, he has the potential to quickly become a terrifying danger.