You must verbally communicate while physically managing to keep up with the dog. Many blind people laughingly remember their instructors as shy, indecisive apprentices who grew into their jobs. Coming out of yourself to work with both dogs and people is a special skill and not one to be taken lightly. A little humility also goes a long way toward becoming a good instructor. Trainers must deal with public ignorance about petting, feeding or harassing Guide Dogs both while in training and while working with their blind handlers.
Trainers field graduate questions and give lectures on dog care and equipment during classes.
This means you'll need a lot of good public speaking and diplomacy skills. Guide Dog instructors are giving blind people mobility tools. There is a sense of magic in the whole process of guide dog training, and yes, history has surrounded it with its own mythology, but when it comes down to it, you are building on someone's foundation of travel skills. Blind people should come to Guide Dog training with some abilities to travel independently. Everyone has differing levels of skill in this regard though.