The Wizarding World of Harry Potter is teeming with magical artifacts, many of which are safely hidden within Hogwarts School of Witchcraft and Wizardry. The school's four founders - Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw, and the infamous Salazar Slytherin - all left legendary items within the grounds. But none are more famous, or more useful to the series' heroes, than those of Gryffindor.
Chief among them is the Sword of Gryffindor. Harry Potter fans will recognize this fabled blade which first appeared in the second book. But where does it come from, who created it, and what makes the Sword so powerful?
What is the Sword of Gryffindor?
The Sword of Gryffindor was made sometime in the 10th century by Ragnuk the First, king of the Goblins, for Hogwarts founder Godric Gryffindor. Like all goblin-made objects, the pure goblin silver sword was imbued with powerful enchantments by its maker. Notably, the blade only took in substances that strengthened its power, thereby making it impervious to rust and other typical kinds of wear and tear. So fine was his craftsmanship, that Ragnuk lied, claiming that Gryffindor had stolen it, and sent goblins to reclaim it.
Gryffindor fought the attackers off, sparing their lives but promising to cut them and king Ragnuk down with the blade if they ever moved against him again. Ragnuk and his people heeded Gryffindor's warning but the belief that the Hogwarts founder was a thief was passed down from generation to generation. Goblins value craftsmanship about all other traits and, unlike wizards, believe that an item's maker is its true owner even if it has been sold. To them, goblin wares are essentially loaned out, not sold, and a goblin may always reclaim a "gift." Years later, during the events of Deathly Hallows, the Goblin Griphook cited this same logic when he demanded Harry give him the Sword as payment for breaking him into Gringotts.
The Sword of Gryffindor share properties with other magical swords of legend, namely Excalibur. Whenever a "true Gryffindor" is in need and acts valiantly, the Sword appears to them within the Hogwarts Sorting Hat, its mythical stone. Thus, the Sword does not remain in one place and has no true owner. Not even a goblin can overcome this enchantment, that's why Neville was able to summon it at the Battle of Hogwarts even though it had been in Griphook's possession.
Harry Potter famously summoned the sword during the events of The Chamber of Secrets when facing one of Voldemort's Horcruxes and Salazar Slytherin's basilisk. After Fawkes the phoenix brought him the Sorting Hat, Harry pulled the Sword out and wielded it against the giant serpent. As a result, the Sword absorbed some of the basilisk's venom which would later allow Harry and others to use it to destroy the rest of Voldemort's Horcruxes.
How Did Neville Longbottom get the Sword?
As a true Gryffindor, Neville Longbottom was able to pull the Sword from the Sorting Hat after Harry Potter gave it to him during the Battle of Hogwarts. At the time of the battle, there were two known Horcruxes still in play - The Lost Diadem of Ravenclaw and Voldemort's snake, Nagini. Harry Potter was the third Horcrux, which wasn't discovered until Voldemort killed him.
Harry, Ron, and Hermione found the Lost Diadem within the Room of Requirement with the help of the Grey Lady, daughter of Rowena Ravenclaw. When Malfoy, Crabbe, and Goyle followed them into the Room, a battle broke out resulting in Crabbe's use of the unwieldy Fiendfyre spell. The runaway curse killed its caster and destroyed everything in sight including the Diadem before the Golden Trio and a frightened Malfoy and Goyle escaped.
Fearful that the battle had grown beyond his control, Voldemort summoned Harry to the Forbidden Forest, demanding that he surrender himself or watch more of his classmates die in the fighting. Voldemort murdered Harry with the Killing Curse, unwittingly destroying the Horcrux within Harry's soul.
Voldemort then paraded Harry's body up to the castle, unaware that he wasn't actually dead. During Voldemort's triumphant speech to the surviving students and faculty at the castle, Neville openly defied the dark lord in a display of valor that earned him access to the Sword of Gryffindor.
In the film, this happens amidst a sprawling fight between Harry and Voldemort that seeming spanned the entire castle grounds. Nagini slithers up to a cornered Ron and Hermione, preparing to strike, when Neville pulls the sword out of the discarded Sorting Hat and decapitates the snake. In the books, Voldemort placed the Sorting Hat on Neville's head and sets it on fire, enraged that the boy would dare defy him. A battle broke out between the survivors and remaining Death Eaters and Neville kills the snake in one swing during the commotion.
With Nagini dead, Voldemort was all out of Horcruxes. The Dark Lord thus died once and for all when the Elder Wand turned on him during a final priori incantatem with Harry Potter, its true owner.
What Happened to the Sword of Gryffindor After Voldemort Was Defeated?
While no specifics have been given about the Sword's whereabouts after the Battle of Hogwarts, it is safe to assume that it is still tied to the Sorting Hat. Thus, it is likely still at Hogwarts, waiting to be summoned by another valiant, needy Gryffindor.