Eirika, Princess of Renais

Graceful Resolve (Whenever this creature attacks, each other attacking creature gets +0/+1 until end of turn)

Whenever Eirika, Princess of Renais attacks, for each other attacking creature, she gets +1/+1 until end of turn

Celestial Twins (You may have two commanders if the other is Ephraim, Prince of Renais)