I've smoked MJ for years. I never regarded it as a pain killer. But it its true that it helps you emotionally cope with the pain. It's as if you can distance yourself from the pain and think about it rationally instead of getting upset about it.
Cannabis-butter is classified as a hard drug in Holland. And I do find it much stronger than just smoking it. I can't remember why it is so different, but it has something to do with the fat in the dairy soaking up the THC or something.