celestial bronze
Godric Gryffindor.
Harry used the sword of Godric Gryffindor.
The sword was Godric Gryffindor's sword.
A broken sword can be a symbol or defeat, or of peace.
With Godric Gryffindor's sword...
Each of the founders have an item that was important to them. For Godric Gryffindor, this was his sword. He enchanted it so that if a true Gryffindor ever needed help it would come out of The Sorting Hat (which also belonged to him).
Ron Weasley stabbed it with the sword of Godric Gryffindor.
Harry Potter told Neville Longbottom that Nagini had to die so Neville Longbottom decapitated her.
Yes, he dives in a freezing pool of water to retrieve Godric Gryffindor's sword.
Harry Potter didn't kill the serpent but Neville Longbottom used Godric Gryffindor's sword to kill the serpent.
In Harry Potter and the Deathly Hallows, Bellatrix Lestrange tortures Hermione Granger at Malfoy Manor for information on Godric Gryffindor's sword.
The other Horcruxes are Marvolo Gaunt's ring, Rowena Ravenclaw's diadem and Helga Hufflepuff's cup. Godric Gryffindor's sword was not a Horcurx.