Just next to Troia is a small bit of space where you can land your airship. Go into the town and get in the pool. Go upstream and enter the hidden passage on the left where you can find an Ether1 and an Illusion hidden in the grass. Once done, leave and enter Troia castle. If you go straight ahead, you will see that the crystal is missing. Return to the room with four guards and go left and into a room where a sick man is resting.
As you go to see him, you realise it is Edward! He wishes to join you again, but he is in no condition to. He apologises to Tellah about Anna�s death, and you will find out that the Earth Crystal is in the hands of the Dark Elf. He gives you a Twin Harp. Now that you have it, leave Troia and save your game.
Leave your airship and head north along the path. In the top left corner there is a chocobo village. Just outside of here is a good place to train because you can cure then catch a white chocobo to restore your MP. Go through the secret passage on the right to get a Gyshal hidden in the grass. When ready, catch a Black chocobo and fly south a bit then east to get to a cave. Land the chocobo, save and enter the cave.