Nowi Seal

First of all i can't agree with your choice on IVs, with that build you're wasting too much stats on spd, if you're going to use her in arena you ill encounter armors most of the time and they will double you most of the time, i have a +10 Nowi with +def -hp IV and she doesn't get doubled that much unless they have Bold fighter and she has 31 spd, so i would recommend a different IV or a different refinement.
For arena also DC won't be that usefull outside rare cases, as things like mage are not that common, and Nowi doesn't need a 300SP A slot to max her score as she doesn't have a prf weapon, a Close def will be better to make sure she can tank even greens when needed.
As her C slot Panic ploy may be a good choice but keep in mind that if the enemy is an armor with a refined weapon it may not work on them, with that in mind Ploys may be good options as with max merges and SS she will reach 33 res which is enougth for most armors