The power of the three lightning had already left his dantian and entered his blood. To say it merged with Chu Feng’s body into one would not be unreasonable, because Chu Feng could feel that the three lightning was different from the other lightning.
The Divine Lightning still in Chu Feng’s dantian, despite being in Chu Feng’s body, could not be used by him in any way.
Whereas the three lightning in his blood were completely different. They didn’t seem to be living within Chu Feng body, but more like they truly coalesced into one with Chu Feng. Their power was Chu Feng’s power.