Narcissists are often fond of accusing another of the very things or attitudes they are culpable of.
While such false accusations are often done in your absence (e.g. to your boss at your place of work, or with friends). Narcissists are also bold enough to accuse you of a trait they know they are culpable of.
They do this in order to make you feel you are wrong and they are blind. But no matter how convincing or confident they may sound, never accept their false accusations.
Of course, there is every tendency you will fall and accept their accusations. But you can refrain yourself from doing so by understanding that they are masters when it comes to convincing or confusing people.