Go to the travel map after you log in. Go to the crossroads and click on the sign 
that reads "Somewhere". 
It will teleport you to an underwater battle sequence. Win all eight fights to 
receive a piece of the sword. Do this to get three pieces in a row. Usually there 
are only two difficult monsters to fight; a Brakel and the last opponent, who is 
either a giant sea snail or a Drakel Rider. You can also gain a few levels along 
the way. Make sure you bring a powerful energy weapon and a fire weapon of some kind,
or just be a level 1 Mage and use the fire attack. This is not recommended for 
characters under level 30.