The knight in shining armor represents all of us in academia who've ever thought we were prepared for battle. You spend weeks fortifying your mental defenses, polishing your knowledge until it gleams... then the first exam question hits you like an arrow to the helmet.
It's the academic equivalent of bringing a sword to a gunfight. Your brain suddenly forgets everything except that one random fact about mitochondria being the powerhouse of the cell. The professor designed those questions in a secret underground lair while cackling maniacally - I'm convinced.