As a way of showing respect to the highest-ranking member of the pilgrimage, the Host asks the Knight to be the first to tell a tale. The tale is exactly what we'd expect from a nobleman like the Knight – a chivalric adventure featuring sworn brother knights, star-crossed love, sword fights, and jousts.
The story is also about how the just and merciful Duke Theseus brings order to Athens. The Duke does his job just like just like a medieval nobleman is supposed to. He could even be the Knight's alter-ego. The Duke shares the Knight's viewpoint and acts as the Knight would were he in this situation. So, in more ways than one, this is "The Knight's Tale."