You let her sit there and look pretty like she's been doing for a thousand years
1. You wait until you pull a Ninian and/or they add more (buff) dragon skills into the game for an epic dragon team.
2. You don't listen to me at all, realize that you are you, say "Screw Arcanite" and 5 star her anyway
3. Do nothing! She can always be useful for Grand hero battles!
True..........................................................
I'll just wait for option 3 because I doubt I can ever get Ninian