Here are my observations about certain classes at that point in the game:
If you aren't seatisfied with your Ninja's behead rate, find a monster with a high Behead chance, have a summoner Contract it, and then use Spirit Pact on it. Many of the monsters with high behead chances become Ninjas, and the Ninja's behead chance stacks with the one the monster gets. (Note that changing class causes you to lose this behead chance.)
Brawlers get the same AC that Ninjas of the same level get, and the 8th floor I believe has enemies dropping Dark Claws as an uncommon drop. Using a Devilish is recommended (either via Spirit Pact or by using that specific spot in the final main game dungeon) so that you can equip cursed items without being cursed. (I have mentioned the idea of a Fairy Brawler in other topics, but that's more of an early game setup; remember that Star Rod?) I haven't tried using one seriously, but if you want that -62 AC on a front line character, try making one and leveling her up until her AC gets that low.
I like my Spirit Pact Nue. That particular monster becomes a Samurai, who has a chance of counter attacking (Swallow Return) when attacked. Furthermore, it naturally has the ability to inflict multiple status ailments when attacking and break the opponent's weapon. If an Archer Polete decides to attack my Samurai, there is a good chance she will lose her weapon and my Samurai will survive. The God Slayer (Ibag 6th floor uncommon) makes a great off-hand weapon here.
Priests are actually decent attackers, even without Physical Attack Power Up. With an Aas Shifter for most enemies and a Comet Hammer (made to do extra damage to Gods via Alchemy) for attacking God type enemies, she can actually do decent physical damage, while being a better healer than my Bishop (who is still good enough as a healer).
As for my Bishop, making her a Fairy helps her act sooner in the round, and having Magic Essence (which only affects Mage spells, by the way) is also quite helpful.
By the way, to level up a new character, the best way to do that is to kill a bunch of Lesser/Greater/Chaos demons in one fight, put the last one to sleep (it won't wake back up), have everybody else run away, and kill the last one with your new character. (An Aura Punch that has been modified to do double damage to demons will allow anyone to do 200, or 300 with the help of a certain Alchemist spell, damage to such demons regardless of class or level.)
Also, don't forget that Honey Restorer works in Ibag Tower, and you should be gaining enough levels to easily relearn it after casting it.