Sword Beam

The Sword Beam is a supposed ability in Legend of Zelda: Ocarina of Time. In several other games in the Legend of Zelda franchise, if you are at maximum health, your sword can shoot ranged projectiles in the direction you are facing. This is notably absent in Ocarina of Time, leading several to speculate on where it could potentially be unlocked. However, if crossing over has occurred, this ability can be unlocked by the player.

Usage
As previously stated, in other games where the Sword Beam was used, if the player was at full health a ranged projectile could be shot in the direction the player was facing by swinging their sword, usually when specifically wielding the Master Sword. However, it may have also had targeting, allowing the player to shoot enemies high up in the sky. This is the most common description of the Sword Beam appearing in Legend of Zelda: Ocarina of Time, though other variants of it's usage have been reported, such as a sword specifically designed to use the Sword Beam known as the "Beam Blade" that could be unlocked through some optional side quest. The damage of the Sword Beam also varies, but it typically does the same amount of damage as the Master Sword.

Unlocking
Several methods of unlocking the Sword Beam (Or Beam Blade by extension) have been reported. In some cases, it doesn't even need to be unlocked and is simply built into the Master Sword. The most common method of unlocking it is by finding the Unicorn Fountain or clearing rumored dungeons such as the Sky Temple, with the Sword Beam/Beam Blade being the reward for clearing the dungeon or finding the location. Some say that unlocking the Triforce would also unlock the Sword Beam, but this is likely just a playground rumor. Another way of unlocking it is by completing a Stop N' Swop with a Key Item, with the Sword Beam being a reward for completing the swap.

Removal
During the development of Legend of Zelda: Ocarina of Time, the developers were focused on combat and Link's moveset. While they initially wanted to remain accurate to previous games, leading to the Sword Beam being coded in, but due to it's nature, it would likely make the game's combat much more trivial and overshadow the closer combat that the developers wanted to create, so it was later removed.