Required quests
Main dialogue
You seem concerned about something. What is it? Hmmm... are you worried that you have not mastered the handling of Battleship yet? Haha, don't worry about it. You just haven't learned the powerful skills that go with the Battleship yet. There's a quick and easy training session for this. Are you interested?
Accept
Okay, here's your mission. You are probably still not very good at navigating around with the Battleship. You'll need to have great control over it in order to use other skills. What I'm suggesting here is... how about observing how others sail with ships, or how to fight while on it? If you really watch for it, you'll figure it out, and you'll be better with the Battleship, right?
Go to Ludibrium and you'll encounter a bunch of Gigantic Spirit Vikings. Observe them carefully, and when you feel like you've picked them apart, defeat 150 of them. I also need to see an evidence from you that you really did slay them all, so I want you bring 50 Spirit Viking Tokens with you. If I see that you have really trained yourself in this session, then I'll teach you a new skill.
Main dialogue
That was a great training session! What was it like facing the Gigantic Spirit Vikings? Weren't they great navigating around the ship while attacking at the same time? I guarantee that if you train yourself a bit harder, then you'll end up much more powerful than them. As a reward for safely completing the task, I'll teach you how to use "Battleship Torpedo".