Well, I figured out a really effective strategy for dealing high damage, effective enough to quickly let me down Yulyana+Mephilia+Barbarossa and Victoria+Artemia+Kikyo. I had Edea go Templar with Conjurer as back-up ability, with boost crit, mp-recovery and buff as support abilities. Then, in battle, have her cast Susano-o to boost her crit to 600%, then use Desperation (I think that's what it's called). Her damage was consistently 4800, or 7500+ when critical. And she hit critical a lot. Suffices to say, she quite efficently wrecked Mephilia before her Susano-o summoning became too much of a problem. Yulyana was next, though either his meteor was less powerful than in chapter 6 or I got lucky.

When fighting Victoria+Artemia+Kikyo, I employed the same strategy, only I gave Edea one of my three Excaliburs to make her attacks holy-elemental. She was dealing 9999 damage to Victoria consistently. Frankly, what made that fight hard was Ringabel needing so much tries to steal everything (even with all steal buffs equiped) to the point I had to hold Edea back from killing Victoria too soon. Didn't help that Kikyo kept killing Ringabel before he could mug, too. I took down Kikyo first (since I stole her item first and she had the least HP). After that, the only real threat was Artemia's multiburst. Victoria's Corpse was annoying, but manageable and with poison immunity she was pretty much powerless while Edea tore her a new one.

It helps that, with all jobs mastered, you have every support-ability available and can mix and match them to suit upcoming bosses. Lightning Amp + Iceflame shield (or whatever they are called) effectively crippled Black MAge Crowe in my fight with him. Poison Immunity on everyone makes Victoria so much easier. I'm sure others could name other effective strategies.

On this I agree with you, Skyblade. It is rather refreshing to play an RPG again that's actually challenging and where finding the right setup of abilities, support abilities and equipment can really mean the difference between victory or defeat. It's a lot of fun. (Would be more fun if the game didn't rehash the same content for 4 chapters, but eh, can't have everything.)