Ok, I've just got the airship.
Everything went alright until the part where I tried to get Aqua Rake from that Chimera. It took me 2 tries before it went like it should. Everyone but Reina where Ninjas and threw Mythril Swords from the backrow. I had to hit it 2 times, wait until it almost killed my party with Aqua Rake, and then throw a 3th Mythril Sword to finish it off. The Sand Worm dies in 1 singel hit from Aqua Rake, but even without Aqua Rake it's not much to fear. The random encounters are getting a bit tougher.