HP&tDH SPOILERS

[Albus]

The ring/resurrection stone: Voldemort put a curse on the ring to protect it when he hid it back in the Gaunt house. Dumbledore adverts to the existence of those protections in the Half Blood Prince, when he tells Harry about retrieving that Horcrux. As to Dumbledore suffering the curse, he admits to Harry in King's Cross that he wanted to use the Resurrection Stone to have contact with Ariana. This caused him to touch the stone and suffer the curse, which Snape's quick work contained in Dumbledore's withered hand. This, of course, led to the plan for Snape to kill Dumbledore at a time of Albus' own choosing.

The Sword of Gryffindor: It was indeed taken by Griphook in the vault at Gringotts. That didn't matter. The sword was enchanted to come to the aid of a true Gryffindor in time of need whenever he shows loyalty to Albus Dumbledore. Remember, in the Chamber of Secrets, the sword was not in Dumbledore's office when Harry was first summoned there early in the book. In the Chamber, however, when Harry said that Dumbledore would never be gone from Hogwarts as long as those loyal to him remained, Fawkes brought the Sorting Hat -- remember, Godric Gryffindor's hat -- to Harry, and the hat conjured up the sword from wherever it might then have resided (one mystery that remains unanswered). Fast forward to the Battle of Hogwarts. Neville Longbottom steps out and has his Braveheart moment, crying out "Dumbledore's Army!" Here comes the Sorting Hat, from which Neville, a true Gryffindor if ever there was one, pulls out the sword. I can only imagine Griphook's reaction as the sword disappeared from wherever he was keeping to be sent to Neville's aid.

The master of the Wand: Draco Malfoy went to the top of the tower with the intention of killing Albus Dumbledore and, in the process, disarmed Dumbledore against his will. That made him master of the wand. Snape killed Dumbledore with Dumbledore's consent. That may or may not have been sufficient to give him mastery over the wand, but it had in any event already chosen Draco as its master. Had things gone according to the plan, Dumbledore would either have died without the wand transferring to a new master or the new master would have been Snape, whom Dumbledore trusted to keep the wand from Voldemort.

Nagini: Voldemort turned Bathilda Bagshot into an Inferius, and then Nagini was stuffed inside of her. Nagini's "speech" in Parseltongue was controlled by Voldemort who, as Dumbledore had observed, had unusual control over her, obviously due to Voldemort's having used her for a Horcrux.