+res -spd Tana help

If you have a flier team, she can still perform decently with it. Otherwise you can build her as an enemy phase unit with Quick Riposte so she will always double during counterattacks. Her Vidofnir is good for this kind of set up. If you use QR seal, you can run swordbreaker so they don't double you, no matter how fast they are. For A skill you can use Fury as it helps her deal more damage and have more defenses. If you don't like its recoil damage, you can do Tri Adept instead. I don't recommend Life and Death because she's quite bulky and LnD ruins her defenses.

If she's like, your favorite character in all of Fire Emblem, I understand. However, really, I don't think there's much to do. I mean, there are some things to do, but not really. Try some phantom speed, fury, brash assault, but there's not much you can do. If you are planning to use her for Arena Duels, I do not recommend it. However, if you are looking for casual, offline story modes and things like that, sure, why not?