Muggles' Guide to Harry Potter/Magic/Sword of Gryffindor

Overview
The Sword of Gryffindor is one of only two artifacts known to have been the property of Godric Gryffindor. The other is the Sorting Hat, which is more a character than an artifact, having been given limited consciousness by Gryffindor.

Extended Description
The Sword of Gryffindor is first seen when it appears in the Sorting Hat in the Chamber of Secrets. Harry uses it then to kill a Basilisk. From then, until the summer before Harry's sixth year, it rests in a glass case in the Headmaster's office.

In Harry Potter and the Deathly Hallows, we discover that the Sword is a Goblin-made blade, and that it had last been taken out of the case by Dumbledore who had used it to destroy a ring. Queried whether it had ever been removed from the case for cleaning, the portrait of Phineas Nigellus had reported that Goblin-made weapons don't need cleaning; they incorporate into themselves anything applied to them which will make them stronger, and the rest just falls away. Harry and Hermione realize that the ring, which was a Horcrux, could only have been destroyed because the Sword had absorbed Basilisk venom. We also learn that a fake copy of the sword had been moved to Gringotts for safekeeping after a group of students, including Ginny Weasley, had attempted to steal it; we don't, at this point, know where the real one is.

Harry then finds it in a pond in the Forest of Dean; as he retrieves it, he is nearly strangled by the Locket Horcrux, but is rescued by Ron. To prove that it is the real Sword, Harry has Ron attempt to destroy the Horcrux. The attempt is successful, proving that they have found the real Sword and that it can be used to destroy Horcruxes. As this is the only certain means they have of destroying Horcruxes, they will retain the Sword in their travels.

They are still carrying the Sword when they are captured by Snatchers, who suspect that they have caught the real Harry Potter and decide to take him and his group to Malfoy Manor for the reward. There, Bellatrix Lestrange sees the Sword and panics, saying that if that is the true Sword of Gryffindor, Voldemort will be furious at them. Hermione is tortured, but sticks to the story that it is fake; Griphook, the Goblin who has been captured with them, confirms her story when he is brought to the scene. Harry and Ron manage to rescue all of the captives and escape with the sword, with Dobby's help, ending up at Shell Cottage.

Harry knows that a fake Sword of Gryffindor was taken from the school and moved to Gringotts, as mentioned above; from Bellatrix' reaction, he reasons that the fake Sword was placed in her vault, and that there is something else there that is extremely valuable to Voldemort. He determines that it is a Horcrux, most likely the cup of Helga Hufflepuff. He discusses with Griphook what is necessary to get into Gringotts and recover this one artifact. Griphook eventually agrees to assist them, but names the Sword of Gryffindor as his price. He feels that the Sword was stolen from goblins and should be returned to them. Harry reluctantly agrees, but does not specify when he will give the Sword to Griphook; he intends to keep it until the last Horcrux is destroyed, and then present it to the Goblin.

Once in the vault, Harry uses the sword to lift the Cup off a shelf. Immediately after opening the door to the vault, Griphook seizes the sword and runs off; Harry, Hermione, and Ron escape on Dragonback.

Viewing Snape's memories in the Pensieve, Harry sees the portrait of Phineas Nigellus reporting that Harry and Hermione are in the Forest of Dean. Snape then retrieves the Sword from a hiding place behind the portrait of Dumbledore, and goes off to place the Sword where Harry had found it, in the pond.

In the second part of the battle at Hogwarts, Voldemort places the Sorting Hat on Neville's head, and sets it and Neville on fire. Neville knows that Nagini must be killed to end Voldemort's immortality, and evidently he asks for help from the Hat just as Harry did, because the Hat produces the Sword once again, and Neville uses it to cut Nagini's head off.

Questions

 * 1) We know there is one fake Sword, that Snape moved to Bellatrix' vault. Could there be more?

Greater Picture
Initially, Harry believes that Severus Snape had sent the sword to the Lestrange vault at Gringotts for safety after a group of students try to steal it, possibly unaware that it was a replica. Later in the book, it becomes clear that Snape actually produced the copy of the sword sent to Gringotts. This implies that it was likely Voldemort who ordered Snape to have the sword sent to Gringotts; Snape sent the copy so that Voldemort would be satisfied and so he could keep the original stored safely in the secret compartment behind Dumbledore's portrait. He then delivered the real sword to Harry in the Forest of Dean so Harry could use it to destroy Horcruxes. Snape almost certainly copied the sword on Dumbledore's portrait's instructions.

It is uncertain whether Dumbledore, or later his portrait, ever completely explains to Snape what exactly Harry will have need of the sword to do. We never hear Dumbledore explicitly telling Snape that Harry has been sent to collect Horcruxes, and Dumbledore, as we find out, has a habit of keeping his secrets very tightly indeed.