Songstress is pretty ideal overall, but Adventurer > Kinshi Knight is probably her best final class if you just want to find her best non-songstress class.
Soar + Lucky 7 is essentially a flyer-breaker (+50 avo vs fliers). With bows beating lances (another big avoid boost) this makes her pretty much untouchable by peg knights for early turns (when flyers are the scariest) so she's great bait and can also heal. Movement +1 is also nice for if she goes back to songstress.
Overall though, anything Azura could do through reclassing... Shigure can do better with similar amounts of effort. He has more options off seals of any type, and better survivability.
Kinshi Knight > Puppeteer is also a good path, especially if you plan on getting the kids a little late. 3 extra units to poke stuff with from afar, maybe stack amaterasu is no joke.
On a personal note though, I'd say her usefulness as a dancer takes a huge skydive after chapter 18/Post-child chapters. The bulk of her usefulness banks on being used as a pseudo-rescue unit to save healers from choke-point stuff.
