The Legend of Zelda: Phantom Hourglass/Getting the Phantom Sword

Now that you have all three Pure Metals, you have everything Zauz needs to craft the mighty Phantom Sword! Head straight for his island and talk to the blacksmith. He will take a look at the Pure Metals, amazed by their quality, and begins crafting a fine blade. It will take a while to finish.

A Pirate's Challenge
Just when you think it's all said and done here on the island, you'll get a visit from the postman, who has a letter from Jolene. She wishes to challenge you to battle one last time. After talking amongst Linebeck and Ciela, head out onto the seas and over to Jolene's pirate ship. She will board as per usual, ready to fight with perfected skills. Face off against her as you would normally, but you'll see she's sharpened her reaction time and both blocks and attacks fiercely. When you finally hit her enough to knock her sword from her, or lock swords and break free, she will pick it back up and fight once more. When you knock her sword away again, she'll admit true defeat and leave the high seas for good, but not before noticing Linebeck hiding in the crate. After Jolene leaves, Linebeck reveals he saved Jolene from a monster in the past and traveled with the she-pirate until he took some treasure for himself.

After an intense battle like this, you'll want to check back with Zauz, as he's probably finished forging the Phantom Sword. Chart a course back to his island.

The Phantom Sword Blade
When you speak to Zauz, he will be busy adding the finishing touches to the Phantom Sword. However, he has only given shape to the blade, not the handle. You need to speak with Oshus to finish the Phantom Sword, so plot a course over to Mercay Island.

The Phantom Sword
Go and speak to Oshus. He will take the blade from Link (almost hitting him as he swipes it) and examine it. After realizing what to do, he asks Link to hand over the Phantom Hourglass. Using his magic powers, Oshus merges the hourglass with the sword blade, infusing it with the hourglass' powers and giving shape to a handle, completing the Phantom Sword, which he passes to Link, nodding that he approves for him to take the sword. Oshus then gives Link and Ciela a final reminder of the upcoming battle with Bellum, revealing that Bellum can predict a person's movement.

Now that you've claimed the Phantom Sword, it will replace Oshus's Sword. This mighty weapon supplies you with the ability to do double damage to any enemy (which doubles Leaf's attack boost) and strike down any Phantom in your way. With the sword at the ready, head back over to the other side of Mercay Island. At the shipyard, you'll see Linebeck has left. Head the path to the Temple of the Ocean King, and you'll find him not far off. He says that he has had a taste of real adventure and wishes you and Ciela good luck against Bellum.

Finally, you are now prepared for a final venture into the Temple of the Ocean King.