THE DEATHLY HALLOWS (I), THE ELDER WAND

Today, The Grandma has been reading about the Elder Wand, also known as, Deathstick or the Wand of Destiny, is an extremely powerful wand made of elder wood with a core of Thestral tail hair. 

In the book it is a thing of legend and is believed to have changed owners throughout history.

The wand's allegiance is thought to be won by killing its previous owner, and therefore its bloody trail had become splattered across the pages of wizarding history, making it the Hallow most easily verified to be a real object. However, Harry discovers from Garrick Ollivander the wandmaker that this popular understanding is incorrect; the Elder Wand actually transfers its loyalty upon the defeat or disarmament, and not necessarily the killing, of its previous master. It will never work fully for a new owner otherwise. This subtle distinction becomes the basis upon which Voldemort is finally defeated, when he believes he has won the wand's allegiance by killing Snape, who killed Dumbledore, while Harry realises in fact he had disarmed the wand's true owner, Draco Malfoy, who had disarmed Dumbledore before Snape killed him. This left Harry and not Voldemort as the wand's true master in their final encounter, even though neither Draco nor Harry had physically possessed the Elder Wand at that point.

According to wizard folklore, the Elder Wand used by its true master cannot be defeated in a duel; this is incorrect, for Dumbledore was able to defeat the legendary dark wizard Gellert Grindelwald, who was the master of the Elder Wand at that point. It also appears, as the wand is somewhat sentient (as are all wands), that it will not allow itself to cause real harm to its true master. If its master dies naturally without ever being defeated or disarmed, the wand's exceptional power will end for any following owner, since it was never won from the former.

The power of the Elder Wand was first shown in history, as Antioch Peverell, the eldest of the mythical Three Brothers, had a duel with an enemy he had long wanted to defeat. He won, and left his enemy dead on the floor; however, after boasting of his unbeatable wand, Antioch was robbed and killed in his sleep by a rival wanting to take the wand. It eventually came to the possession of Mykew Gregorovitch, a Bulgarian wandmaker. Gregorovitch boasted about possessing the Elder Wand, believing it would boost his popularity, and he tried to reverse engineer its secrets as he faced competition from Ollivander. It was stolen from him by Grindelwald, a former friend of Dumbledore who sought to impose wizard power in the world. Grindelwald was defeated at the height of his power by Dumbledore, who in his later years considered it the only hallow [he] was fit to possess, not to boast of it or kill with it, but to tame it.

Dumbledore arranged his own death with Severus Snape, intending in part for Snape to end up with the Elder Wand. Because his death would have been pre-arranged and not the result of his defeat, he had hoped this might break the wand's power. However, Draco Malfoy disarmed Dumbledore before his death at the hands of Snape, causing the plan to fail; the wand was buried in Dumbledore's tomb, but Draco had already unwittingly become its new master, even though he never took physical possession of it from Dumbledore. After Harry disarms Draco (even though Draco is not using the Elder Wand), the wand becomes loyal to Harry instead.

In the final book, Voldemort seeks the wand in order to defeat Harry -his previous wands having failed-  and breaks into Dumbledore's tomb to claim the wand as his own. During the Battle of Hogwarts, he understands that the wand is not performing for him as legend says it should, and mistakenly concludes this is because it had become loyal to Snape when Snape killed Dumbledore, and would only become loyal to him upon his killing of Snape. He therefore kills Snape, and believes the wand will thereafter serve him and be unbeatable, but during his final duel with Harry his Killing Curse rebounds and he dies -as Harry had warned him- since the Elder Wand will not allow itself to be used by him against its true master.

After Voldemort's death, Harry uses the Elder Wand to repair his own broken holly and phoenix-feather wand, which he says he was happier with. He decides to return the Elder Wand to Dumbledore's grave, feeling that if he dies peacefully, its superior power will end. In the film, Harry snaps the wand in two and throws the pieces off a bridge.

Ron stated that the Elder Wand would be the Hallow he would choose, simply because it is the unbeatable wand, arguing that it was only dangerous to the brother who requested it because he kept on talking about his ownership of it and encouraging people to fight him. Hermione (who said she would choose the Cloak) is sceptical, reminding him that the Wand, by its very nature, would make its possessor overconfident and braggadocious.

More information: Wizarding World

 I was fit only to possess the meanest of them,

the least extraordinary.
I was fit to own the Elder Wand, 

and not to boast of it,
and not to kill with it. 

I was permitted to tame and to use it,
because I took it, not for gain, 

but to save others from it.
That wand's more trouble than it's worth.

Harry Potter