I have to say I'm not happy with these update times. I was so confused when the chapter started. I thought Kanda's false memories were real but couldn't remember reading them and thought I missed a chapter so I went back to previous chapters and found nothing only to continue 217 to find out the innocence guy planted them. -_-
Anyway, I think Kanda becoming general goes something like this:
Tiedoll said that Kanda has been surpressing his power, which makes total sense. He hates the order for what it did to him and Alma, but he is an exorcist, so he'll do his duty, but he doesn't want to do anymore than required for them.
If I remember correctly, if it was even mentioned, we knew from the start that Kanda was one of the strongest non-general level exorcist and that's why he's the one that's always on missions.
He also had a number of attacks for Mugen, he just doesn't use them because they require his life force the more power he had to use.
Kanda has been a exorcist before, he is obviously possessive of Mugen, it's natural that he was somewhere close to critical point from the start of the series. Or as it went on and he was able to kill a Noah by himself.
Side note: for the person who didn't know what 'critical point' is- it's when an exorcist and their innocence has a Schro rate of over 100%. It's also a requirement to become a general. I can't tell the exact timeline cause this manga takes forever to update, but it feels like it was mentioned a very long time ago. Allen has also reached general level.
I'm happy to see Tiedoll and definitely happy he came bearing news.
I'm happy Kanda's becoming a general. But sadly Gerenal Yu sounds way better than General Kanda. He is not going to like that.