Zeniba hands Chihiro a new hair-tye and says "this will protect you"...what does it ultimately protect her from? Does it protect her in her future endeavors? Also, there are two times at the end of the movie that the hair-tye catches a glimpse of light and shines -- once right before she enters the tunnel and second while taking one last look back into the tunnel. Knowing it has special properties, what's the significance/function of this spell-bound hair-tye?