Macey was a mace made of Gronckle Iron that Tuffnut found and named in Smoke Gets in Your Eyes. Tuffnut cherishes Macey a lot and has a weird habit of speaking to "her". Macey later appeared in Dragons: Race to the Edge several times before it was destroyed during a battle against Dragon Hunters in Twintuition.
Macey is a shiny mace made of Gronckle Iron. Like most maces, it is covered with spikes and has a long wooden handle. Being made of Gronckle Iron, it is shinier and has fewer blemishes than most other maces seen in the franchise.
Tuffnut found Macey on Trader Johann's ship and instantly loved it. He bartered for it, though it's not certain with what. That night, Smothering Smokebreaths, introduced to Berk by Dagur, stole most of Berk's metal, including Macey. When Tuffnut woke up, he was heartbroken at her disappearance and accused Ruffnut of stealing her, insisting she had been jealous of Macey. While they were trying to figure out what happened to all the metal, he showed Hiccup and Astrid Macey's favorite spot; a cabinet decorated with flowers and leaves. He recounted that Macey loved watching the sunset; or the wall, depending on which side he placed her. In the end, the metal was recovered, and Tuffnut was overjoyed to be reunited with Macey after defeating the Berserkers and sending the Smothering Smokebreaths back to Breakneck Bog.
When Tuff thought he was turning into a dragon, he gave away his prized possessions to his friends, including Macey. He presented Macey to Snotlout, who pretended to be grateful, but quickly tossed it aside as soon as Tuffnut looked away.
Tuff brought out a box of weapons with which to help defend the Edge, saying Astrid could have her pick of any of them, except of course Macey, and a couple of other things.
Though not seen, Macey is mentioned when Hiccup shares his plan to sneak into the Dragon Hunters' base. Tuff asks if Macey can come along on the mission, saying she's been longing for some action.
Macey was seen in a flashback being used by Tuffnut to "interrogate" Gothi.
While Gruffnut is impersonating Tuffnut, he tells Ruffnut that she can carry Macey while on patrol, tipping her off that maybe her "brother" isn't who he claims to be. During the skirmish on Barf and Belch's back while in the air, Tuff calls to Ruff to toss him Macey, with which he then manages to defeat Gruff and knock him off the dragon's back to the waiting Hunter ship below.
Macey was the focus of this episode. Tuffnut unintentionally broke it when trying to destroy a dragon-proof chain with it. Saddened and unable to sleep, he and Ruffnut went to Hiccup's hut in the middle of the night, begging him to fix it in his forge. When he insisted it could wait until morning, the twins went to the Northern Markets to find a blacksmith who could fix it right away. The twins managed to convince a blacksmith to fix Macey after telling a lie that they are Dragon Hunters, and took down Hiccup, the leader of the Dragon Riders, with it. While Tuffnut was telling his story, Macey was then stolen by a Dragon Hunter and taken to an island where Project Shellfire was under construction. Disguising themselves, the twins followed and tried to recover Macey, but Ruffnut finally advises Tuffnut that maybe it would be for the best if he were to let Macey go, to which he abandons Ruff to find Macey on his own.
Later on, Tuffnut recovers Macey and uses it to battle several Dragon Hunters who have learned of his true identity and captured Ruff. When Hiccup and the others arrive to save the twins, they get trapped in a flooding cage, and Tuffnut throws Macey into the rotating gears to prevent more water from flooding into the arena so his friends wouldn't drown. But the gears were too strong, and Macey was eventually crushed in its grip, leaving only her handle intact. When the Dragon Riders returned to the Edge the next day, the twins gave Macey's handle a Viking funeral. Ruffnut shot a flaming arrow to her funeral boat and missed, but Hiccup has Toothless burn it with his plasma blast.