I've checked Raven's Spreadsheets and, as far as I can ascertain, you can change Ramza's skills, stats, equipment, level, zodiac sign, gender and even his stat growth but I didn't see anything about which skills he has already learned for the first battle. Considering how much time I've already spent on looking for something trivial, I've decided to let it slide and use a ghetto fix instead. I just hope I don't run into any other issues like this with the rest of the game.