sf2char.txt - Starting stats and equipment for player characters.
sf2duel.txt - A complete listing of possible duel combos, along with the difficulty of getting them to combine.
sf2item.txt - Item data. Weapons, armor, etc.
sf2jutsu.txt - Charting the likelyhood of characters learning magic after battle.
sf2misc.txt - I think these are stat growth rates.
sf2monster.txt - This behemoth is a dump of some of the game's monster data. Instead of one big nice table, there are lots of smaller ones scattered about, apparently one for each area or screen or whatever. And yes, every time a Sidhe Bunny appears its entire data block gets duplicated. "Scene Drops" are items that aren't tied to a particular monster, but that you can get just for having fought in a particular area. (Scene drops labeled "#1" seem to have a 100% drop rate.)
sf2minimonster.txt - A simplified bestiary, with duplicates, attacks, and scene data removed. sf2waza.txt - The party battle "waza tree", or how to spark new arts in party battles. Yes, the stuff Cross Slash was supposed to spark got dumped in Double Slash's list. Yes, this is probably a bug. :)