I didn't know that drawer opened up after you gave the old man those items.

Well, wait until Disc 3. Go find the little red thing in the Corel Desert and fly into it. Hopefully you will win the battle. You will win Desert Rose. Next go use the sub to say hi to the jolly green weapon swimming around underneath the ocean. You'll get the Earth Harp. Wasn't that easy? Some think so. (I certainly don't!)