John Maxwell encourages leaders to assess weaknesses they not readily see, by assessing the four symptoms listed below

http://www.johnmaxwell.com/blog/leadership-blind-spots

Do you have any blind spots?…If you answered no, you now know where your blind spot is! Okay, I think most of us would acknowledge that we do possess blind spots. We assume there must be some areas where we “don’t know what we don’t know.” And we suppose that our personal blind spots have an effect on our lives – quite possibly a negative effect.

But what happens when a leader has blind spots? It affects so many more people than the leader alone. It can have a far-reaching impact — on the leader, his or her followers, and the entire team, department or organization. Here’s my definition of a blind spot: an area in someone’s life in which he continually fails to see himself or his situation realistically. This unawareness often causes great damage to the person and those around him.

Here are just a few basic blind spots exhibited by leaders:

1. A Narrow Perspective
2. Insecurity
3. Out-of-Control Ego
4. Lack of Character