Training the two wasn't too difficult while they were traveling to the north.
Their faults were quite obvious for Shiro and it was just a case of telling it to them while demonstrating in a spar.
Celeste was too 'honest' in her fighting style. There were no feints at all and if she charged, she'd commit to that charge until the end. While her power is good, it's like fighting a train. You know where the rails are, all you had to do was step out of her path.
During the first few spars, Celeste was confused as to why she couldn't even come close to hitting Shiro so she tried to use feints but she used too much strength and tired herself out before even committing.
Shiro had to spend some extra time teaching her about balancing the two in a fight.
