I'm not sure if it's a bug or not, but when i was killing Lematan (the final "boss") everything was ok but when i lowed him to 50% HP, he ported to the ship and stopped attacking.
Imgs:
(http://i.imgur.com/A0OoK1W.png)
(http://i.imgur.com/SsTCcyA.png)
(http://i.imgur.com/8NZQ10W.png)
(http://i.imgur.com/wACPkt5.png)
Edit: i did it again with other character but in this case i used Ancient Legacy Sword and the final "boss" was normal this time
(http://i.imgur.com/DotybKQ.png)
If isn't a bug sorry for post.