Ragnir

The default state of this living weapon is a war hammer of colossal proportions, scaled to suit Loki, who carries the build of an ancient giant. White bandages cover the thin handle, which rises from a raised plate at the center of the head and runs long enough to be gripped with both hands. As for the head itself, it is rectangular, fashioned from bluish-gray metal, and weighted like an enormous sledgehammer.

When it shifts into its Beast Form, Ragnir becomes a huge squirrel roughly matching the size of the chest that once held Elbaph's legendary fruit. The body is plump, the tail large and curled, and three whiskers sit on each cheek above prominent buckteeth. Its fur is white, broken by bluish stripes that travel from tail tip to the crown of its head, a thick light-blue band in the middle flanked by narrow rows of dark blue triangles, the central stripe narrowing to a point between the eyes. A hybrid configuration also exists, in which the full hammerhead juts up from the top of the squirrel's skull.

Though it appears unable to speak, Ragnir is wholly sentient, and for hundreds of years it stayed true to one charge: guarding Elbaph's legendary fruit and rejecting everyone it judged unfit for that power. When Loki finally bested it in combat, those exacting standards were met, and the overjoyed hammer swore itself to him the moment it handed the fruit over. Capable of acting and moving on its own even while shaped as a hammer, it is a fearsome guardian, since across centuries no would-be claimant ever managed to slip past it. During their first clash it held off the legendary prince for a stretch, and though it lost, his old hammer broke in the exchange. Its durability is striking: a full-strength Supreme King Haki blow from Loki's prior weapon only knocked it into squirrel form and raised a lump on its skull, whereas that hammer shattered. Its mass is so great that in hammer shape it can drive itself through Aurust Castle's stone floor, and Loki noted that even Hajrudin could not lift it.

Empowered by the Ratatoskr model of the Mythical Zoan-type Risu Risu no Mi, Ragnir can shift at will into either an ice squirrel or a hybrid that fuses the squirrel with the hammerhead, the squirrel shape dwarfing its hammer size. That same fruit grants its sentience and self-movement. It generates ice and freezing mists able to instantly freeze a target, and per Loki, nothing it freezes can thaw until the weapon permits it. By colliding ice crystals together it produces and amplifies lightning, pairing it well with the Nidhoggr-model Ryu Ryu no Mi. Once it summons lightning, the whole hammer becomes wrapped in electricity that shocks anyone nearby.

In the distant past the hammer consumed a Zoan fruit that let it become a giant squirrel and gave it awareness. From then on it was charged with safeguarding the Devil Fruit referred to as the national treasure of Elbaph, sealed within a chest in a guarded vault of Aurust Castle. There it kept vigil for hundreds of years and deemed no one fit to eat it. Over that span Nerona Imu came to know of Ragnir's enduring wish for a new master.

Fourteen years ago, at his father's request, Loki went to seize the legendary fruit so Harald could not eat it while under Imu's brainwashing. As Loki opened the chamber, the hammer hurled itself at him on its own, missing and shattering a pillar. It then drove itself into the floor hard enough to nearly drop the prince, and kept maneuvering to attack until a clash with Loki's own hammer overpowered it. Forced into squirrel form and dazed, Ragnir judged Loki worthy and let him eat the fruit, delighting in his first transformation. A weeping Loki then used Ragnir to strike down Harald.

Six years ago, after Shanks captured Loki and returned him to Elbaph, Ragnir stayed beside the giant during his confinement, shackled to the Treasure Tree Adam. During the Final Saga's Elbaph Arc, once Luffy and Zoro nearly freed Loki, he grabbed Ragnir and struck the tree, calling down lightning into the Underworld, though his threat proved a bluff as he collapsed. Later, fully freed, Loki used Niflheim to freeze a giant Draugr, then rode up to the Sun Realm with Ragnir perched on his head. The trio battled across the Sun World, encased Imu and Manmayer Gunko in ice with Niflheim, and clashed again with Imu, who recognized the weapon and remarked that the weapon had finally secured a master after such a long wait, provoking Ragnir to raise an ice cloud through which Loki fired bolts of lightning.