Yeah I discovered this little trick, then posted it to a apprentice guild post to much the same effect
Still least you had the pleasure of discovering it for yourself
I like to do it with a straight thrust to the face from a single handed sword now days, it just feels more satisfying that way
so what you're telling me is to pass them by and kill them while at it... wow i should try that
It's not so much "pass them by", more like "horse charge them and hit them while they fall", the horse charge breaks their block and leaves them vunerable to the hit from the weapon. You just need to be hitting them a glancing blow with the horse so they fall where you can hit them with the weapon. If you ride straight over them they go under the horse.
Usually works best on the right side of your horse as the swing from that side goes lower. And keep looking at your target through the whole move as that gets the swing lower (because you'll be looking down by the time it hits).
With a little practice you can do it with any mele weapon with a half decent range (maybe not a knife) including a lance thrust, which is particularily satisfying.