Although Old Wang already knew that this woman was no ordinary person, he still underestimated her. Because the baptism that followed made Old Wang fully realize just how colossal the price of underestimating a woman could be.
When Old Wang knocked away the white light with his blade and discovered that the white light was actually a silver hairpin, a sense of crisis regarding life and death simultaneously rose in his heart. This sense of crisis was a special ability obtained by Old Wang after cultivating the fourth style of the Chaos Five Decisions, the Chaos Giant Transformation.
It was akin to a type of detection that allowed Old Wang to sense the threat level of an enemy or opponent unconsciously. That's why, when Old Wang faced Mo Can, he didn't feel the slightest bit of fear. This was because the detection told Old Wang that Mo Can would not pose too much of a threat to him. Similarly, when facing Yao Wumeng, the detection indicated danger but not a fatal one.