Why doesn't Voldemort use Gryffindor swords as his Horcrux? Because Voldemort was never able to get his hands on Godric Gryffindor's sword. At the time that he was searching for objects belonging to the Founders of Hogwarts, the Sword of Gryffindor was not in the public view.
The sword was impregnated with basilisk venom in the chamber of secrets which gave it the power to destroy horcruxes. Turning the sword into a horcrux would make it weaker, thus impossible with goblin made material.
It is interesting to note that the sword is the only one of the main relics of the Hogwarts Founders that is not a Horcrux but one of the few things that can destroy a Horcrux. Slytherin's Locket, Hufflepuff's Cup and Ravenclaw's Diadem are the other relics, but are also Horcruxes.
Voldemort was fixated on having his soul split into seven pieces, he assumed that it would provide him with additional protection. This is why he did not split his soul more by creating additional Horcruxes.
Thanks to Harry's actions, Godric Gryffindor's sword became a weapon that could be used against the other Horcruxes. Voldemort's failure to corrupt Harry, or the sword by making it a Horcrux, eventually spelled his downfall.
The Dark Lord — aka Voldemort — created seven Horcruxes in an attempt to sustain immortality.
This medallion is a replica of Voldemort's horcrux that originally belonged to Salazar Slytherin and copied by Regulus Black. The medallion comes in a display and with a letter written by Sirius Black's brother, Regulus, who gives to Harry Potter a clue to destroy the horcruxes.
Dumbledore knew that destroying Voldemort's horcruxes was the only way to truly defeat him. He believed that Harry was the one person who was smart, courageous, and perhaps lucky enough to find and eliminate all the horcruxes.
Voldemort intentionally made six Horcruxes, but when he used Avada Kedavra on Harry, he unintentionally created a seventh Horcrux. Instead of dying, Lily's love for Harry created a counter 'curse' known as Sacrificial Protection and saved Harry.
Voldemort thought Snape was the owner of the Elder Wand. Using Avada Kedavra while the Elder Wand was resisting Voldemort was already a risky business, but using it against the true owner would be suicide (as Voldemort would find out when he used the Elder Wand against its true owner: Harry).
Question number one: Why didn't Dumbledore just give the sword of Gryffindor to Harry instead of leaving it to him in his will? He knew even before his death that Harry would need the sword to destroy Horcruxes, and he must have known that the Ministry would not let Harry get the sword.
Third, Dumbledore had no way of knowing beforehand that the Horcrux in the sea cave was a fake, and that he would not need to actually destroy it.
Yet despite the danger of his mission, and despite being hated by most of the wizarding world, Snape held on to the one thing that kept him going: the safety of Lily's son. He even sent his Patronus to guide Harry Potter to the sword of Gryffindor (a known Horcrux-killer) in a nearby lake.
At the beginning of this book, he measures it against Lucius Malfoy's showing he still has it and it is intact. Dumbledore explains to Harry in book 4 that since both wands contained a tail feather from Fawkes the phoenix, the couldn't face each other as they'd refuse to destroy each other pretty much.
The important part here is living. An Horcrux, is usually an object. Inanimated and definitely non-living. The killing curse could, most likely, still damage the object because of how powerful it can be, but not really destroy it unless the object in question is fragile.
Bellatrix was given a fake sword to keep in her vault, where the Cup of Hufflepuff (another of Voldemort's Horcruxes) was. When the trio was taken to Malfoy Manor by the Snatchers, she saw the real sword with them and thought the trio broke into the vault and tortured Hermione to get her to talk what she knew.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
Her sacrifice gave Harry the power of love, a protection spell sealed with the blood spilled by her death.
So why wasn't the Horcrux residing in Harry's head destroyed when he was bitten by the Basilisk? The answer is simple: He didn't actually die. Fawkes quickly healed the bite wound with his phoenix tears just in time. Case closed.
Severus Snape wanted to teach D.A.D.A. for years, but Albus Dumbledore denied him the job repeatedly, partly for fear of Snape straying back towards the darkness, and partly to keep him around for longer, given the curse on the position.
As Rowling explained in a series of tweets, Snape loved Harry's mother, Lily, and his unrequited affection drove him to resent Harry's father, James — and by extension, Harry himself.
Salazar Slytherin and his descendants were fluent in Parseltongue — the ability to speak to serpents.
Unknown date between 1946 and 1979: While hiding out in a forest in Albania, Tom Riddle murders a local peasant and sends a piece of his soul into Rowena Ravenclaw's diadem (a.k.a. tiara). It becomes the fifth Horcrux.
Reputation. The ability to actually speak Parseltongue — not just imitate it as Ron Weasley did — was considered an attribute of a Dark wizard, which was partly due to the fact that both Salazar Slytherin and Lord Voldemort possessed this ability.