Not necessarily. The "hitherto unknown" bit refers to the specific type of dragon, not the transformation. The type of dragon was "hitherto unknown" because before Dragomas demonstrated his transformation no one knew that type existed, but says nothing about when Dragomas first showed off that ability.
Kadon preferred that armies bake their dragons from scratch, but in a pinch he allowed that store-bought was fine too.
What do you mean by 'you need a dragon to do it'?
What we know about Cathay heavily implies they would not even think about teaching a foreign human how to transform into a dragon. They do not even seem to do it with the Shugengan. They also seem like they could be very offended by a human pretending to be a Cathayan dragon. Less so the western dragons, but the Cathayan dragons definitely.
Yes, I know it refers to the type of dragon. My reading of the passage is that the type of dragon was not known until the aforementioned leadership duel with Alric. Hence Dragomas could not have shown off that ability until he used it in the Supreme Patriarch duel. In my eyes the phrasing of the sentence ties "hitherto" to the "one-on-one duel."
Kadon is known for both his shapeshifting into monstrous forms (Transformation of Kadon) and binding them (Arcana of Kadon/Scrolls of Binding).
It means that the Shugengan dragonblooded on vacation in Marienburg that happened to wander beyond borders will have something to invoke if border control decides they are suspiciously witchy.
Is there a reason for that we know of?
I think Boney had already written some stuff on Cathay before TW3 came out and said the thing with Azyr. It's possible that for quest purposes they do in fact have institutions for all the Winds.
Lizard people, it's just what they do, I'm told.
Aqshy and Chamon are practically allowed too. Those are the winds that Zhao Ming's alchemists use and his status as favorite son of his mother allows them to flourish across the Celestial Empire.
I believe GW has said that the dragons don't think it is safe for humans to use the other winds. Alchemists get by because of sibling favoritism.
That is essentially agreeing to lose to your siblings. They've been set in their positions for over four thousand years. It's fun to joke about it, but of the siblings only Yin-Yin cares about outsiders enough to venture beyond the borders. The wind preference would match. But she is also very haughty and very unlikely to give up the fight to be Dad's favorite child. None of them would, but Yin-Yin is one of the least likely to.
Though there is, of course, 2 dragons that are completely undefined by canon.
Out of the dim mists of my empty mind, I think humans were said to be believed not to have suitable temperaments for any of the others (in the sense that the results were perceived as not good).
Dhar is so anti-prestigious that you'll be killed on sight for it everywhere worth living, and it still attracts envious eyes. Power is power, and getting locked in to doing the same thing as everyone else is a lot less attractive when you know you could have specialized in any of the winds that have healing spells.
That was before Total Warhammer Cathay was revealed, so it is possible that Johann was just mistaken about what Yin and Yang meant.
