User blog comment:Enriant/Heaven and Hell/@comment-26982641-20160602080446/@comment-26271908-20160606204355

Sure, that's speculation all Knights have a Mark. With this one I agree. However, they being trained by Cain don't makes them more powerful or immune, considering that they are Black-Eyed. Having the Mark is the only really good explanation to define why they are so stronger than the Black-Eyed Demons when they themselves are. Abaddon's fear of Gadreel was because she haven't seen an Angel for a long, long time

Sure, I would like it to be not true but Reapers were retconned to be Angels. That is nothing to be done about this. That's nothing wrong on the wikia. It is made to register information about the series, and the series retconned the fact. It's very simple

I don't think that Castiel was higher than Naomi, but rather they are in the same level. Both are high-ranking Angels, the difference between them is that Naomi was a smart girl while Castiel was not. He was able to stand against Raphael because he was the one who received thousands of souls from Crowley. If not, Raphael would surely destroy him easily. He did it once. Doing it again would be an easy job, Seraph or not

And, no, Seraphim can't kill Knights. Knights can only be killed by the First Blade, who is empowered by the Darkness itself, who is their source of power, so I would say that only another Primordial Being has the power to kill Knights