+HP -ATK Shiro

An Attack bane isn't his worst, but I think Def bane is. Mainly because he loses out some precious physical bulk to properly tank and take on most physical threats like Ayra and Mia.

Anyway, he can run the following:
Weapon: Bright Naginata
Assist: Swap or Reposition
Special: Bonfire or Ignis
A: Steady Stance 3 or Steady Breath
B: Quick Riposte 2/3
C: Threaten Atk 3, Threaten Def 3 or Tactic Def 3
S: Close Defense 3

Using only the first options of this build idea, his Bonfire will add roughly 25 bonus damage upon triggering and he still hits fairly hard with it. If you have access to Steady Breath fodder, then you may run Ignis instead.

In conclusion, yes, he's still fairly usable.