Oh, that didn't surprise me at all. That's been building since "Order of the Phoenix", when he was so keen to join Dumbledore's Army. He wanted to fight those who had so brutally attacked his parents. I'm glad his Gran finally saw him in action, and could be proud of him!
Actually in the Socerer's Stone (Philosopher's Stone) Neville's extra 2 points awarded by Dumbledore, for having the bravery to stand up to his friends was what put them over the top for the House Cup. He has always been steadfast and brave. And the actor in OOTP has grown up to be able to play him still diffident but courageous and kinda cute. He'll really enjoy doing the last HP movie.
I can already picture the slo-mo swing beheading the snake.
Actually, the final battle will probably be about 30-40 minutes long. The whole forest thing will have to be condensed, and the Dursleys will probably be disposed of very quickly. The first chapter, if it's there at all, will be about 2 minutes tops. It'll be there only to show the downfall of the Malfoys and the horror in Draco's eyes.
On the other hand, I'd love to say a reaction shot cut in to the line:
"The rightful owner of the Eldar Wand is ... Draco Malfoy!"
(Come on down! You're the next contestant on Beat the Dark Lord!)