A game where planning ahead is key. Also fishing.
I went ahead and picked up two more Silver Knives and gained a level for Ryu off-camera. Go back and talk to Mygas once you have, and your reward is this handy little spell:
...Which won't be much use in the next dungeon, but will when we need to pass through a mountain later with ice-vulnerable Tar Men (who also give quite decent XP). However, I'd recommend taking Ryu out of apprenticeship with Mygas immediately after you learn Frost; Int is basically useless as a stat and +1 AP per level really isn't worth it to get -1 Power and Defense growth each level. There are far better ways to gain AP, trust me.