How to get Biggorons Sword:
•Go to Kakariko Villiage as an adult. Talk to the lady with the cucco allergies. She will give you an egg to watch for a while.
• Play the sun's song to make one day pass.
• The egg will hatch and you will have a full grown cucco.
• Then go to the building near the Well.
•Talon is laying on a bed asleep so equip your chicken and wake him up.
• Return the cucco to the lady and she will be delighted and offer you a rare blue cucoo, Cojiro.
•Take the chicken to the Lost Woods.
•When you enter take the first left. An ugly man will be sleeping on a stump. Use Cojiro to wake him up. You will receive an Odd Mushroom from him.
•Exit the forest and get on Epona and ride as quick as you can back to Kakariko Village.
• Run quickly up to the Potion shop near the watch tower. There will be a doorway at the back, go through that.
• It leads to the backyard, and the back entrance to another building. Go into the other building and run up to the old hag.
•Offer her the Odd Mushroom. She will then mumble and make a potion for you.
•Take the potion back to the Lost Woods where you got the mushroom. Instead of the man being there a little Kokiri girl will be.
•Talk to her to trade the potion for a Poachers Saw.
•Leave and head to the desert and jump across the broken bridge.
•Once you get across you will see a man off to the right. Offer him the saw, and in return he will give you a broken Biggoron's Sword.
• Take the broken sword to the very top of Death Mountain.
• There you will find a very very large Goron. He's having a problem with his eyes so he can't help you unless you take a prescription to King Zora.
•Go to Zora's Domain.
•If you've thawed him out already then talk to him. If not then you need to get some fire and do so.
• He will inform you that they are out of the Eye Drops you seek, but he does have an Eyeball Frog.
• Take the Eyeball Frog to Lake Hylia quickly as you have a short amount of time to do so.
•When you get there go to the Lake Side Laboratory and offer the Frog to the the old man.
•He will make you a potion after much talk about thinking it's food.
• Run back to Epona as fast as you can and ride her to Kakariko Villiage.
•Now you must climb Death Mountain as fast as you can. I personally recommend using the magic bean plant to ride most of the way up the mountain.
• Give the Eye Drops to the Big Goron and he will give you a claim check!
•You can either wait 3 days to pick up your new sword, or play Sun's Song and have 3 days pass much quicker.