I watched an anime movie 4-8 years ago. Here's what I can remember:
It's about two brothers, they go to school. But the older brother has a sword and has to find gems/stones which make it more powerful. The younger brother wants him to stop (because of the evil that comes with that power I think).
Now I can't remember what was up with the stones at this point, but the brothers entered some kind of other world (it looked very bright I think) and had to fight, I THINK the older brother wanted to have the last stone which the younger one had.
I don't remember the ending.