It means that you will need to work on any fear of rejection. That you will need to learn how to be ok with being vulnerable. To be brave when you feel vulnerable to work past that instead of deciding to discard when these vulnerabilities surface.

Usually, with a narcissist their biggest fear is that of abandonment and some kind of rejection. So that leads to looking for ways to blame others for any failures in order to protect that very deep insecure part. Typically, the insistence with a narcissist is that of THEIR being the one who is discarding, the failure must belong to someone else, so much so that they engage in a smear campaign so as to protect that hard shell they built up to protect that part of them that is very vulnerable. And because there is no such thing as a perfect person, the narcissist first wants to learn weaknesses "just in case" so they have what they need IF they begin to feel vulnerable.