Written and Verbal Communication
Not only do you have to be able to communicate clearly to give financial advice, you also need to inspire trust and develop a strong rapport, otherwise no one will trust you with their money. This is not a matter of putting on a trustworthy front; while some people clearly misrepresent themselves in order to attract business, such practices are both morally wrong and usually less effective. You have to actually have integrity and good judgment. But if you can’t communicate well on all levels, how will other people be able to tell that you're a trustworthy person?