I love the idea of wyvern armor, be it aesthetic or have actual stats (though I'd prefer stats :P). It could be pretty simple too, and just have head, body, feet(claws).

Have the helms do things such as force it to use only specific ele breaths + enhanced damage.
Have body focused on defensive stats, HP, etc.
Feet focused on offensive stats, or even being unique and adding the ability to change damage type (slashing, piercing, blunt).

At least that's how I'd like to see it.