Let's break it down for a bit. Lettering is the most notable change. It's totally different than the "transformers script" in the previous 4 movies.
Who is the last knight? It appears that the sword that is in the title is the one that Optimus found on the alien ship. I'm guessing he is the last knight?! But it can't be because he ends up in Age of Extinction heading into space looking for its owner. hmmmm......Let the hunting begin.