Status Update, including my Thief gallantly stepping up to the plate:
Spoiler: Click here to view
Fighting my way through the Marsh Cave was not easy, but I was expecting that much. I handled the Piscodemons relatively handily, got my ass back outside and used the Cottage I had found inside the cave. Good thing I did, because I went straight to the Western Keep to return that king's Crown I had found in the cave. The dark elf king guy took me completely by surprise, and it was a rigorous battle during which my Warrior, and White and Black Mages all died. Sly, my Thief, was the only one left alive, complete with about 20 HP, and no Phoenix Downs, Potions, or other means to heal himself. So I crossed my fingers and attacked... and the 32 points of damage I did was enough to bring the big guy down. I was slightly miffed that the rest of my party missed out on the EXP, but it was a tremendous effort, and I was surprised I had beaten him at all.
So, is the White Mage supposed to be a guy or a girl? I named mine Angela, because for whatever reason I've always associated white magic with females in Final Fantasy games... but now that I take a good look at the sprite, I guess it could be a male, in which case I hope he at least has a good sense of humor about it.