[Endoperez]

That's like saying that if you cut a dragon's clawtips off with a sword, it won't hurt, because they're just nails.

Every feather starts from flesh and bone, and if the feathers are cut or even just in the wrong order, flying is harder or even impossible. So no, I don't think that'd be a good reason to give them air shield.

I'd be for boosting their stats, though, at least defense. They can fly, and I'd imagine that'd be at least as helpful in battle as being mounted (faster movement, you are/can be higher) - and being mounted gives you +3 defence.