The use of Divine Will was not solely to identify items that were invisible to the naked eye. Strong Divine Will could affect one's soul or even destroy one's soul!
As of now, Zhou Donghuang had managed to cultivate Divine Will as he was now at the Dharma stage. For Dharma adepts who were at the Primordial Soul stage and below and had not yet managed to cultivate their Divine Will, once they used their Divine Will, they would be able to affect the other party's soul. Even if they were unable to fully destroy the other party's soul, they could at least impact it.
Once one's soul was affected, if the person in question were to face something extremely impactful, then their soul would be lost.
Think about this: If two Dharma adepts dueled and either one of them were to utilize their Divine Will, at a key moment should they choose to use the Divine Well to impact the other party's soul, what would happen?
