Well, the key is to be honest. What is your weakness?
The next step is to spin it.
Besides the "I work too much", which is sort of the cliche SM answer to this question, my answer is "Cheerleading casts does not come naturally to me.. I expect actors to come in and be ready to work and come in with a good attitude. In my experience, I know this isn't always the case. So, what I do do is try to creative a positive upbeat work atmosphere, where actors like to come to work. Using a light touch and a sense of humor helps me avoid the situation where I need to cheerlead.
Taking a negative, spinning it, and explaining how I compensate for this.
Saying "I take really lousy blocking" is probably not the best thing to lead with.