Best build for +atk/-def nowi ( weapon refinery stat also)

Refinery bonus: +Spd or +Def
Support:Pivot/Swap
A:Fury3/TA3/Steady Breath
B:QR2-3/Wrath/Vantage3
C:Threaten Res/Threaten Atk
Special:Moonbow/Aether(If steady breath is a slot)

Those skills are the one that suit her best,just choose depending on how you wanna play her.

best Skill set will be

Weapon
Lighting Breath+ (Def+)
The Reason For Def+ is that it fixes the bane and she will be decently bulky but if you want you can make Nowi full out damage dealer with Atk+ but Def+ is the better option for survivability

Assist
Doesn't matter that much maybe swap pivot or reposition

Special
Moon bow
I choose Moonbow because of easy activation and not to mention the weapon you using either lowers the res or def once the weapon is refine so the lower stat of a range unit will be lowered making Moonbow the best Special

A Skill
Fury 3
Fury 3 will increase her Survivability further with def and increase her atk which is amazing making to do damage to most sword lance and low res green units which I will definitely choose

alternative skills could be
Triangle adept to make red units nothing to her or Steady Breath to make her Def amazing when attacked but you will have to Sacrifice a brave Ike or a Shiro

B Skill
Renewal 3
Renewal 3 just make Nowi a mega tank because of its healing of every second turn which is amazing if you Nowi to be hard to kill. Alternative skills can be QR(If not using Fury), Wrath or Vantage 3

C Skill
Threaten Res 3 is the best choice because since most Physical units have low res they attack your Nowi the Nowi tanks and those MASSIVE Damage taking away a lot of HP

S Skill
Close Def 3 is the best choice for her to tank major hits because it can stack with steady breath making Nowi a OP Tank so I suggest this skill,
Also Distant def 3 can work too for tanking mages and archers easier

Stats with this Build
HP 50
Atk 52
Spd 30
Def 34 (40 if attacked with close def 3) (if remove Fury 3 with Steady Breath + close def = 39 Def)
Res 30