I didn't either... it was awfully mysterious. I made a picture based on it and it turned out real weird...
I'm kinda annoyed with all the people going "It looks like StarWars!" and "poncho!!1!1" 343i just needed a way to show Chief and hide him at the same time, if you know what I mean. I also think the cloak was to show off their graphics skillage.
If I were to make a watermark and apply it to my art (well, which is unlikely because i'm lazy and I have no people stealing from me yet XD) I'd probably put it in the corner so that it dosen't cover up the art so much.
Yeah I understand that, but still I wouldn't overdo it. The way it is now if good. If they really want to steal a picture they will, no matter what. Even if there's an ugly-ass watermark in the middle of it. I saw plenty thieves getting around that problem by editing it out with shitty paint shills or by pretending to be said artist. So I don't really see the point of over-uglyfying a drawing as nice as yours.