In this chapter, Jesus hammers on the Pharisees for demanding a sign. The disciples still don;t get it, and Jesus accuses Peter of being Satan.
Jesus also heals a blind man. Skeptics point to this healing and others in Mark where Jesus uses some physical means as evidence that the Jesus legend grew over time. "The original Jesus," they say, "wasn't a divine miracle worker, just a folk healer with delusions of grandeur." (Mark was the first Gospel to be written.)
That totally begs the question of the healings themselves, of course. Mark also contains stories of Jesus healing without physical contact, for example, the Gentile girl in the previous chapter and the paralytic in chapter 2. Perhaps Jesus knew that for this person to accept Jesus' ability to heal, He needed to provide some physical act.
God does a lot of things to help those of us whose faith is weak.