Thanks for the tips, guys. So far so good - I have cleared out Debir except for that evil dude in the castle. He kept casting Phoenix which was really screwing with my no losses routine. I think it's 18/18 no losses fights now, although I'd be lying if I said I didn't have to reload a few times.
My tactic so far has been to prioritise Dragon experience, so I've taken two levels of Training and thus the dragon is already at level 6, even though Amelie is still level 4 (nearly 5). I took one point of Treasure Searcher as DGD recommended, and the rest of the points have gone into Crushing Blow (400-500 hit points, which is excellent for Debir). The problem for the Warrior early on is that getting spells scribed is really difficult. I finally managed to get Distortion 1 but I really could use Healing (obviously Order 1) or Phantom. The problem is that for the low hp units I am using it is hard to keep them all alive.
My leadership on leaving Debir for the first time is 820 and my team is Swordsmen, Royal Snakes, Priests, Inquisitors and 2 Royal Thorns. I really need Paladins and/or Royal Griffins sooner rather than later, because I can't keep up the no-losses with units with low hp.
Off to Scarlet Wind.