His medicine staff consists of horse hair, hawk feathers, fur (possibly otter), and whatever his specific medicine is. His staff holds his medicine and that gave him his power. Medicine men were often seen as threatening because they could send bad medicine to you or someone close to you if you did something to offend them.
Medicine men were, and still are, believed to hold great power over people's health. They can both cause or cure your illness. Many tribal members still seek the help of revered medicine men and women when they are in bad health.