Aeroblades

The Aeroblades are a powerful group of weapons. The Ninja obtained the Aeroblades, anticipating to use them against the Ghosts after getting them from Ronin. They have the ability to defeat ghosts when slicing through them.

Appearance and Abilities
The Aeroblades resemble a shuriken-like weapon that are usually dull and non-colored. However, when touched, they glow in bright colors, usually depending on the person’s element, which allows the weapon to have the ability to defeat the Ghost Warriors when they come in contact. The Aeroblades are circular in shape with three sharp points on their sides.

The Aeroblades can also be used for battling enemies that are not ghosts, being used as regular weapons. The Ninja and Ronin have used their Aeroblades as shurikens, and they are large enough to be used against other weapons in melee combats, just like shurikens also.

Stiix and Stones
When the Ninja confront Ronin in his shop in search for the Scroll of Airjitzu, he misdirects them towards buying weapons from him, which leads him to offer them the Aeroblades, but at a price they can't afford. Later at night, they attempt to steal the scroll from his shop, and are confronted by Morro and multiple Ghost Warriors. The Ninja and Ronin used their Aeroblades to battle the ghosts while everyone battles to get the Scroll of Airjitzu.

The Temple on Haunted Hill
Ronin used his Aeroblade to save Nya from one of Soul Archer's ghost arrows.

Peak-a-Boo
The Ninja used their Aeroblades to battle the Ghost Warriors while climbing the Wailing Alps.

Kingdom Come
The Ninja battle Morro and his ghosts for the Sword of Sanctuary. Ronin uses his Aeroblade to block one of Soul Archer's arrows from hitting Nya.

The Crooked Path
Jay used his Aeroblade to destroy Ghoultar.

Grave Danger
The Ninja left their Aeroblades in R.E.X., leaving them without any weapons.

Curse World - Part I
Ronin and the Ninja didn't use their Aeroblades but they were seen with their owners.

Curse World - Part II
The Ninja used their Aeroblades to battle the Ghost Warriors and The Preeminent.

Public Enemy Number One
Ronin briefly used his Aeroblade to capture Jay.

Appearances

 * 70730 Chain Cycle Ambush (Ice Aeroblade)
 * 70731 Jay Walker One (Lightning Aeroblade)
 * 70732 City of Stiix (Fire Aeroblade)
 * 70733 Blaster Bike (Earth Aeroblade)
 * 70734 Master Wu Dragon (Creation Aeroblade)
 * 70735 Ronin R.E.X. (Fire Aeroblade)
 * 70736 Attack of the Morro Dragon (Fire and Lightning Aeroblade)
 * 70737 Titan Mech Battle (Ice Aeroblade)
 * 70738 Final Flight of Destiny's Bounty (Creation Aeroblade)
 * LEGO Ninjago: Masters of Spinjitzu
 * "Stiix and Stones"
 * "The Temple on Haunted Hill"
 * "Peak-a-Boo"
 * "Kingdom Come"
 * "The Crooked Path"
 * "Grave Danger (mentioned)
 * "Curse World - Part I"
 * "Curse World - Part II"
 * "Public Enemy Number One"
 * "Operation Land Ho!"

Trivia

 * Lloyd is the only Ninja (other than Nya) to not obtain an Aeroblade due to being possessed by Morro.
 * The color that the Aeroblade glows seems to be related to the wielder's element, despite Cole's, Jay's, and Zane's glowing their respective colors when first touched by Kai.
 * This also does not explain why Ronin's glows green (it may be the default activation color).
 * The Creation Aeroblade never appeared in the series, and Ronin's Aeroblade never appeared in the sets.
 * It's possible that Ronin's Aeroblade is the Creation Aeroblade, which could explain why it has the default activation color.
 * The 70738 Final Flight of Destiny's Bounty set has the Earth Aeroblade on the box but the Creation Aeroblade is in the actual set.
 * This makes the Earth Aeroblade the only Aeroblade to appear in one set.
 * Somehow, Cole's Aeroblade could still destroy ghosts, even when it was turned into a ghost along with him.