Build or fodder?

Level her up to 40 with her base kit and see how you like her. She doesn't really have anything worth foddering since you can get Drive Atk through grails (Groom Marth) if you really needed it and the seal is better used elsewhere.

34 Res at base is quite nice for a mage tank build.

Sure. Those are good IV's. With +Res she can easily run a ploy in the seal slot.

All she needs is Fury/Desperation. Or if you don't have fodder for that, death blow works or Lancebreaker in the B skill.