If you've taken the time to learn some of the enemy's attacks, the Blue Mage can come in handy. Blue magic can range from small pointless moves to strong and powerful attacks, healing magic, and even magic to boost your own stats. Also, with the Blue Mage you can look at your enemy's stats so you can determine the best way of defeating it. Make time to learn your enemy's attacks. You'll regret it if you don't.