Lets talk about your newest party member, Cooke. She comes with white magic which is great for healing but not so great for doing damage. If you haven't done so already equip her with an accessory that will let her cast black magic. It will not take her long to level up and get Prayer a darn useful ability as it grants her a free healing spell to whomever she wants but it can only be cast while in combat. If you want to save her MP then find a way to work it in. Cooke is really good at healing (both in and out of combat) as her healing spells heal for more then other party members.