+spd -def Tana op busted???

Depends on what you want her to do. The builds you see on the character pages can be taken into account, but don't forget that you can also make your own build, or put in things that other people haven't taken into account.

Sounds like good IVs for a Firesweep build. Defensive stats matter much less when you don't take counter attack. Dumping 20 K feathers might not be too cheap but it's far less than other units need. Depending on your luck Hit and Run may be scarce.

I’d say her best build would be a firesweep build, but you could use a budget build if you don’t have Roderick or enough feathers to 5* a 4* variety. Vidofnir is viable on its own, and through buffs from your allies you could run a desperation build where she would hit hard and fast, and be able to tank on enemy phase if needed. Close def 3 seal makes her much better for a melee unit, and fury allows her to hit the desperation threshold quickly. Hit and run/drag back let her engage and get out of enemy range too.

My Tana is +def which is fantastic with her weapon skill. because of this i run Close def for an A skill along with the CLose def seal for essentially triple close def which is fantastic. it puts her base def of 29 up to 48 when she gets attacked by a melee unit.

My entire flier team is desperation brave weapon build except for cherche who is brave axe and axe advantage build.
Once they are in that mode, its almost 1 shot everybody.
Elincia,
Cherche
Tana
Cordelia