There are those that are so egotistical that they do not recognize anything but their strength and refuse to believe that they have any weaknesses. "She-Devil" is a perfect example of that type of person.

On the other side of the coin, there are those that have absolutely no self-confidence who believe that they have no strengths only weaknesses. Example: People that stay in abusive relationships because they think it's what they deserve.

I hope this expounds enough on what I meant!