Bug? - Armorsmith <> Weaponsmith

[Tinu]

I'll start with a statement, that this might be entirely my own fault, but the result is weird, so I post it here for you to check or confirm that it's working as intended.

So I was an Armorsmith when I recently accidentally clicked on Myolor Sunderfury at the Great Forge. And to my surprice I saw a chat offer, if I want to become a Weaponsmith.

I was like:" hm, weird, I though it cannot be combined with Armorsmith..." So I clicked on it and of course ignored the warning and confirmed thinking that it will fail because I'm already an Armorsmith...

To my surprise the chat filled with a ton of lines "You have learned how to create ... xxx".

Result is: I'm no longer an Armorsmith. I can now take the Weaponsmith/Armorsmith quest again. So far I can see it as intended behavior.

Now the weird part: I'm still a BS265 as before and all of the Plans I ever bought and learned, or skill I learned thru the quests to become Armorsmith are still available to me. But most of the plans learned by the trainer are not (I can re-learn them from the trainer).
The really weird part is, that some plans like Rough Sharpening Stone and Rough Weightstone, e.g. those trained by trainers are still known by me as well. So I guess there is something fishy with this whole thing.