The random terrain/mob melee glitch is something that happens rarely, so is hard to reproduce and fix. The game decided that with the momentum of your motion after swinging, that you hit something just right and flung you into the far reaches of space. Interesting glitch, but definitely a bit rage inducing when it happens to you. This is the first time I've seen it happen with a sword though, that was some launch and air time you got there. This is also the first time I've ever seen it not kill you instantly from the impact itself, maybe the sword had something to do with it. Normally you die immediately and are flung. Nice video, maybe it'll help them figure out something.