While I wasn't the biggest fan Majora's Mask personally, I'd be damned if I didn't admit it had the best looking swords in the series. Arguably, the Great Fairy's Sword is one of the coolest and most colorful. Not to mention one of the most deadly as it wields four times the attack power of a Kokiri Sword.
An interesting caveat to this sword is unlike many other swords in Zelda adventures, it's not a standard sword. Players must equip it to an item button. To use its spin attack, players must rotate the analog stick on the controller instead of traditionally holding down the button. It's unsure if this was created on purpose or if it was a programming error.