As much as I love this theory and think it is very interesting, I do hope it isn’t true.

One of the reasons King Hassan is one of the most if not the most badass servant is his lack of mystery yet prowess in his abilities. KH isn’t so much as an actual person but a myth, even among his group the Hashashin don’t even know if he’s real or not. The whole point of KH is that he’s the Hassan which kills Hassans, he’s a warning to those tempted to stray the path. In fact, no Hassan WANTS to see him because if they do, that basically means they failed and they’re going to die very soon.

I also want to note that KH isn’t bad at assassinations at all. In fact, you have to consider he does his job while wielding a large broadsword while being like 8ft tall. The dude literally sneaked into Ozymandias’ reality marble and decapitated him before he could realize what the hell was going on. He’s actually so good at it to the point where he can literally be seen as an avatar of death and anyone who is about to be killed by him gets this “premonition” similar to a bell’s tolling which announces their inevitable demise