The Sword of Sanctuary is a mystic weapon which was utilized by the Ninja and Morro. It was formerly obtained by Morro and wielded by him, as well as Kai and Ronin, but at the end of the fifth season, the Sword of Sanctuary was left with Lloyd. It is also the second clue to the location of the First Spinjitzu Master's final resting place.
Morro uses the sword to win in an encounter with the Ninja. When Kai confronts him, Lloyd fights Morro's possession and briefly emerges, giving his friend the sword. Before Morro recovers and attacks Kai, the latter uses the sword to see Morro's next move and escapes with the sword.
The sword is now in the hands of the Ninja, and they proceed to search for the location of the tomb. Meanwhile, Ronin receives a message from the Ghost Warriors, in which they tell him to steal the sword in exchange for his soul. While the Ninja are busy in the tea shop, Ronin attempts to steal the sword from them, only to realize Nya had discovered his motives and was guarding it. After a brief fight, where Nya sees a future of Ronin kissing her, the bandit outsmarts Nya and escapes with the sword. He then gives it to Morro, who uses it to stab the Scroll of Airjitzu, while revealing the precise location of the First Spinjitzu Master's tomb.
Morro enters the Tomb of the First Spinjitzu Master and used the sword to pass the first two tests. In the last test, he wields the sword in battle with the Ninja, unintentionally trapping himself in a barrier of ice stalagmites.
After catching up with his rivals, Morro would threaten to kill Lloyd with the sword if they don't give up the Realm Crystal. After being tricked, they would have another fight, with Morro using the sword.
Morro fights Lloyd with the Sword of Sanctuary during the Ghost War. Near the end, Morro tries to finish Lloyd with the sword, but Ronin arrives in his ship and saves Lloyd by pouring his savings of gold coins on Morro, causing him to lose the Sword of Sanctuary.
In the final battle between the Ninja and the ghosts, Ronin uses the Sword of Sanctuary to eliminate some of The Preeminent's tentacles, while the Ninja round up the people of Stiix in a boat. Morro then arrives and battles Ronin. After the fight Ronin loses the sword, but when Morro goes to retrieve it, Lloyd attacks and they begin to cross realms.
In the end, Lloyd is brought back safely to Ninjago and then reunited with his friends and family, where he is left with the Sword of Sanctuary. He tells his team that he saw a future event on his sword, telling him that Morro had to return alone, not only so Lloyd could defeat him by giving him a temporary victory, but also to teach him the true meaning of being the Green Ninja.
As a weapon, the Sword of Sanctuary can be used in combat. It can also be used as a tool to cut through obstacles.
The sword possesses the power of precognition, which makes its wielder see their opponent's next move before that maneuver is made. This gives its wielder a crucial edge in anticipating an enemy's next maneuver, as happened with Morro, Kai, and Ronin. The sword also seems to hold the power of fate; Morro uses it against the Scroll of Airjitzu to locate the tomb, and Lloyd sees in its blade that the key to defeating Morro was to allow him the victory of returning to Ninjago alone.
As effective as it is in combat, however, the Sword of Sanctuary does have one drawback; it cannot reveal an opponent's true motives. Kai discovers and utilizes this weakness successfully by indirectly wielding his Aeroblade at Morro—which he sees and thus ducks—while actually targeting his ship's mast, crippling Morro's means of escape and allowing Kai to catch up to him.
- The Sword received a lot of criticism, as it gives too much advantage to the one wielding it.
- The Omega appears to be the only character in the series that the Sword of Sanctuary doesn't work on.
- In the Korean-translated shows, its name translates as "The Holy Sword."