Aether
Aether is Ike's Up B attack in Super Smash Bros. Brawl. He first throws his sword in the air. During this time, he can take damage, but cannot flinch. After the sword hits the apex of its trajectory, he jumps up, catches it, and comes hurtling towards the ground. It appears functionally similar to Kirby's Up B move, the Final Cutter. The trajectory is very vertical and has no "DI", however it is useful for recovery, for as Ike's sword reaches the top before Ike, it can hit anyone attempting to edge hog and give Ike an opening.
Aether is a move specific to Ike in the Fire Emblem games. In both games Ike appears in, it involves throwing his sword upward, jumping, catching it and coming down with a spinning cut that heals Ike equal to the damage inflicted, and a second rising strike is performed as Ike puts space between himself and his opponent. This second strike ignores the enemies Defense score. However neither effect is applied to Brawl.