I'm lucky in that I work for an organization that identifies areas that employees need to be competent in and offers a number of courses aimed at getting better in those areas. Also managers have a list of courses that are required. Stuff like basic Finance, people skills, interviewing techniques, management skills, etc. As a new first-level manager I'm still working my way through all this stuff and I am learning a lot.
If it were not for this I probably wouldn't even have realized the areas where I was lacking. Instead I've taken a ton of these classes and learned a lot about myself.
If I were designing something like this I'd start with a personality profile that would let the user understand where they needed improvement and how to also improve the areas where they were already strong.