You know, I've seen some people do some stupid things, and any tool or aid can be misused. I've had people say dumb things to me, seeing me ride with spurs. (Mostly younger greener kids, that don't understand the use of spurs, and consider them cruel under any circumstance.) I was taught to ride on roping and cutting horses, and spurs were always just part of riding... another form of communication, "Power Steering" as Grandpa used to call them. If a horse is trained for them, they are very effective, with minimal use. BUT! I have seen some people jump on one or 2 that had never been ridden with spurs, and saw one horse whip his head around, bite the guy's pantleg, and pull him right off the saddle.
As far as other things-whips, poles etc. The most creative thing I ever saw was a guy with a 2"x2", 3 foot long piece of wood, with a water balloon taped on the end. He used it One time, on a mare that reared up every time she was cued to back. Cracked her right between the ears as she went up, balloon popped, the water ran down her head, and she never reared again. He said she quit 'cause she thought she bumped her head and was bleeding.
My Dad bought a quarter running mare off the track way back when, in AZ, that had a nasty habit of backing FAST when he tried to mount. So, he pointed her butt at a big ol' saguaro cactus, and... well, she stood still for mounting after that.
It's funny to me, people spend all this time and money for expensive "Training Methods", because they don't want to "Be Cruel" to their horse, and want to bond with a 1200# puppy dog, when if you treat them like a horse, and respect the fact that they are NOT dogs, you get alot more done in alot less time. JMO.