hrmm....good question.
insecurities are a weird thing, because people are not always insecure about their weaknesses. alot of the times its just a distorted perception (i.e. very attractive women being insecure about their looks)
insecurities usually cause people to address them(if they can be. obviously there are things that can not be changed).
it's usually about how much a particular weakness affects you and how self concious you are of it.