It is worth noting that sometimes it is even advisable to run Cassiopeia's skillset over Andromeda's. You get slightly weaker healing and Defense buff, and in turn get access to her Chaos Magic without using a valuable EX slot. Resuscitation is not as overpowered as it may seem at first glance.

So yeah, D'art, Mordred and Hercules should be unlocked before Andromeda.