well there is a training weapon still used by many koryu for certain kata sets and for training matches called a fukuro jinai. It's a rod of bamboo split into 8-12 sections and covered in leather which is laquered or left matte. When you get struck with one, you don't end up with injuries, but a good wake-up call. The worst that can happen to you is a friction burn if the leather is unlaquered or a bruise, maybe some swollen fingers if you're hit on the hands, but that's part & parcel of training. The conceptual design hasn't really changed in 500 years.
Ive ben hit square on teh head by one those. It hurt but not a alot. Ive been hit harder witha kendo shinai. It was a wake up call but yeah id rather be hit with a fukuro jinai than a kendo shinai.