This move involves Mega Man throwing a circular saw blade towards his opponent. The blade can be thrown in 8 different directions, including backwards. Metal Blade can also be caught out of the air by opponents or picked up after being thrown into a solid surface, acting as a throwable item and retaining its straight trajectory when thrown again. If Mega Man throws the Metal Blade straight down into the ground, he can immediately pick it back up and use it as an item, which improves its utility. The blade vanishes after traveling a moderate distance, and only one blade can be in play at a time, unlike the original Metal Blade from Mega Man 2, which could be spammed and traveled the length of the screen.
Unlike most other projectiles, Metal Blade travels through opponents and hits multiple times, its hitbox staying active until the sawblade disappears. This means it will do more hits against larger opponents (this can be most obviously seen when using Metal Blade against Master Core's beast form), though in normal battles it will usually hit an average of two times. Because it has high hitstun and locks opponents in place, Metal Blade is generally a good projectile to start combos with and can create openings for Mega Man to approach.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
The Metal Blade was first introduced in Mega Man 2 as the weapon of Metal Man, one of the eight robot master bosses in the game. After defeating Metal Man, Mega Man receives the Metal Blade as a special weapon. The weapon is infamous among the Mega Man fanbase for being a near-gamebreaking weapon; it can be thrown in eight directions, has a large hitbox, does not disappear if the damage is enough to kill the enemy (allowing several kills with a single shot), and can be used 112 times before running out of weapon energy (or infinitely by way of a glitch). In addition, it serves as the weakness of Bubble Man, Flash Man, and destroys Metal Man himself when he is rematched in Dr. Wily's Castle with only one shot when playing in Normal Mode (two shots in Difficult Mode), and is more effective against Wood Man than the Mega Buster (though there are other weapons more effective against Wood Man). There are, however, certain bosses that are completely immune to it, and the final boss restores health from getting hit by it (and every weapon excluding Bubble Lead, his weakness).
One of the move's variations, Hyper Bomb, was introduced in Mega Man as the power of Bomb Man. The bombs that Mega Man throws with this power travel in an arc, then set off after some time (unlike in Smash Bros., they would not explode automatically on contact). Hyper Bomb is the weakness of Guts Man in Mega Man and the weakness of Ice Man in Mega Man Powered Up. In addition, Mega Man Powered Up was the game that allows the hyper bombs to explode on contact, but can only be aimed while playing as Bomb Man.
The second variation, Shadow Blade, was introduced in Mega Man 3 as the power of Shadow Man. The blades are shurikens that can be fired in five directions in its first appearance. Only one Shadow Blade would appear at a time if Mega Man shoots it. Shadow Blade is the weakness of Spark Man as well as Magnet Man.