Nah, none other, I haven't fought him anywhere else before. But one thing of note is that for the entirety of this match that happened, I don't believe We3da was killed by anyone and it was a good group of us that day, like 15+ players or so witnessing this.
Something that didn't jump to me initially is that this could be speedhack where instead of increased speed the player slows down himself. That puts players in a desynced state (where they're just unhittable). The stuttering and slow running speed would be the signs as someone with a bad connection don't display that kind of behaviour, more like extrapolation issues (the timeout effect on players essentially, till their client updates the server on their position)