They can admit to themselves that they’re a bad friend. They can entertain the possibility that they take their parents for granted. They will consider the instances in which they act selfishly in relationships and won’t try to shift the blame onto circumstances or other persons. They’re able to acknowledge that they have a problem with anger, or jealousy, or kindness.
Notice also that I said “confront”. The strongest people don’t just see their weaknesses, they face up to them. They act on their perceptions. They attack their weaknesses and challenge themselves to transcend them, to be better, to do more.