On this floor you will begin running into automatically Dividing enemies. Without a Mystic Knight, you're likely to Divide them repeatedly, resulting in very long battles. Each Monster killed is worth plenty of gil, but very little Experience (though you will gain plenty of Job Levels). Silencing them won't prevent them from Dividing, but Paralyzing them will. Poison is also useful since they have a lot of HP. Aside from the Death Claw, they resist every Element you have access to, so stick to Spells like Bio if you want to hurt them. There simply is no easy way to kill these guys. The fact that they make you fight them without Mystic Knight Weapons is just cruel.