Donating a Wo Dao+ for a better good

I was lucky enough to get a +Spd -Def Soleil, with her being one of my favourite children from the Fates universe. So I planned to make er a pseudo Mia, with Heavy Blade, Wo Dao and Luna. With the new update, refining weapons opens a new dimension of building possibilities.
My question is: what Wo Dao upgrade should I give my Soleil? An attack+ so Heavy Blade acrivates more often, and because the red shine that it gives fits her and the Wo Dao really well? A speed+ so she can reach 41 speed (with spd +3 seal 44spd), with an ugly green shine? Or a defense+ to make up that -4 defense loss by the bane and so she gets a bright yellow shine?
Basically indecisive between looks and efficiency. Help.

(I will also use Firesweep strats don't worry, I just want to mess around with different builds)