Continuity question for Harry Potter 7 readers.

I just finished reading the last Harry Potter book (I know, took me long enough, well, I wasn't in any rush) and one thing confused me a bit. After robbing the goblin bank, I was under the impression that Griphook the goblin made off with the sword as payment for his services; as far as I know, the sword was never retreived. Come the end of the book, however, Neville pulls it out of thin air to decapitate the snake. Did I miss something? Where did the sword come from?