Although Lex looked extremely confident in himself as he walked out, perhaps even arrogant, the truth was that he had not lowered his guard one bit, even when he technically defeated the suit of armor.
If there was one thing he had learnt during his training with Cassandra, it was that he always had vulnerabilities in her eyes. Although he had grown tremendously, aided not only by his own efforts but by the boost in comprehension provided by his cultivation technique, in her eyes he always had room for improvement.
It was like she had her own version of his left eye, just that instead of seeing the vulnerabilities due to laws, she saw his weaknesses.
The problem was, if she could do it, who was to say that others who had even a modicum of her experience couldn't do the same. They wouldn't even need to be as good as her, just identifying one weakness was enough.
