I've been told since when I started University!
"You should be able to assess yourself."
I'm not! Or, at least, not without great effort! But I perfectly agree that is important to know how to assess your personal ability in order to reach new goals!
To assess my personal intercultural competence was particularly difficult, because there are many things that work in our mind without we are conscious of. Schemes, stereotypes, help you to comprehend the world around you, and they are not always a negative thing, but we are not always conscious of how much they influence our perception.
So, to assess my awareness of negative reactions to differences was quite a problem, how can I be sure that I do not think my reactions are due to the cultural differences when it is so?
Our mind sometime reacts in a very particular way (take an exam of social psychology if you don't believe me!) and we cannot be aware of that.
Anyway, I really reckon it is useful to value these different things (Awareness, Knowledge, Attitude, Language Proficiency and Skills), to stop and think about it let you know that these kind of mechanisms exist, and then maybe next time you'll be able to suspend judgement, or just to be aware that your judgement is due only to the cultural difference!