For the issue of the conflict, my one current idea I think is decent that would involve airships is thus:

When the war started Rose and Eve realized that they could not face the full might of Kantle, especially alone and to ally with each other would also be unacceptable or whatever attempts at an alliance broke down. However with Kantilian mobilization near completion they couldn't very well do nothing so they decided, in this one act of co-operation, to destroy the road that connected the islands to nullify Kantle main military advantage, it's armies. 

However Kantle couldnt not just sit back and accept this. The Kantilian leaders had declared war and to have this war peter out without doing anything? It would have been humiliating and would greatly damage their reputation amongst their own people, especially the ever suffering poorer classes of Kantilian society. So they decided to invest in ways to fight the other islands without the need of the road, and thus the airship comes in. I think at first they would have begun with what they already knew, the taming and riding of the flying beasts that traversed the empty skies between the islands. However they found that this was not enough so they decided to construct the first model airships and this is where we are at in terms of airship technology, still in it's infancy. 

On the other side Rose and Eve, thinking their work was done and the greatest threat to their existence nullified, went back to their islands and occasionally sent threats to each other and maybe had a few sky duels by their sky-rider people, maybe even raids. Like North Korea and South Korea. They would also do this with Kantilian sky riders too. Still most of their leadership now believe that Kantle is not a threat but maybe a few amongst their ranks know of the rising threat of the airships. Or maybe the airships are common knowledge amongst the leadership but not treated seriously, with a small ignored minority saying they are.

EDIT:

Also, do you think this kind of thing would fit the image of a Rosilian soldier/knight? 

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