How many Black Knights (Black Wings Generals) are there really?

I've factored that in. But then explain the screw up by Nexon in the Alliance gathering, wherein Aran is portrayed as female?

As I said before Aran is changed between male and female a lot. In the flashback of fighting the Black Magician Aran is shown as male, when you go into the past Aran is shown as a male.

And, I wouldn't put much weight into those images, they completely left out entire classes, guess those classes no longer exist because they weren't shown, eh? Do those images show up in game? If not then Aran is canonically male because he is shown as male two times within the game, anything outside the game doesn't count. Also, to use your excuse about Demon Slayer, Aran is shown as male on his class creation icon.