Help with Mia

I really don't see this working. She needs all the atk she can get.

Personally, I think -SPD Mia is worse because she loses her niche as being the fastest unit in the game before skills and she can make up that attack with Resolute Blade. I use a -SPD/+DEF Mia and she is still amazing. Although my build is Resolute Blade, Reposition, Glimmer, Life and Death 3, Vantage 3, Hone Atk 3, and either Spd seal or Heavy Blade 3 to patch her speed and she reaches 56 attack at neutral. But since you have -ATK...

If nothing else, use Fury, Moonbow, Desperation or Vantage (your preference) for your -Atk Mia. Fury to help patch the attack and boost her other stats. If you want to use her Flashing Blade, then use one of the speed sacred seals to increase the chance of speeding up her special if you want to use a special with a longer cooldown. It is just that in arena, a lot of fast swords are looking to have well over 40 speed in upper tier arena.

I know it is not ideal, but if you want to use her, you can build her to kill with her special. She still has more attack then similar native Wo Dao user and more speed thanks to Resolute Blade (Athena, Karel, Marisa).