If we expect to be able to actually apply our percussive techniques for self-defense, I think it's necessary to “temper” our bodily weapons to some degree. And for those who train in percussive martial arts, that's exactly what the various hand/arm and foot forms are; they're hands and feet but they're also weapons with which we can defend ourselves if the need should ever arrive.
However, a large number of martial arts devotees don't bother to “temper” their bodily weapons; they don't strengthen them so that they can withstand the force of our own blows and cause adequate damage to a given target. It's akin to carrying a sword (or any other weapon). To begin with, you wouldn't buy a cheaply made sword that's been fashioned out of low quality steel, would you? It could easily bend or break when you need it most! And you'd take care of it; making certain that it's sharp and well oiled to prevent rusting.
I'm not saying that you necessarily need to turn your hands into small cudgels but the various techniques that you favour probably need to be strengthened and toughened to some degree. For instance, how often does a spear-hand appear in your forms? Probably not frequently. Could you actually use it? Are your fingers (and your technique) strong enough to make it effective? Unless you have actually trained this technique using special training routines, it likely won't work too well for you. I used to tell students that such techniques are “specialty techniques” that require special training if they are to be used efficaciously. I later realized that ALL techniques are “specialty techniques”.
Even your sword-hand (aka. “knife hand”) needs to be properly tempered so that you can strike powerfully without discomfort or injury. Simply knowing how to do it isn't enough. The same is true for kicks and even strikes made with the elbows.
I'm not saying that you must train your techniques on a well made striking post (although I'm a strong advocate of this device) but you MUST temper your techniques properly. Imagine relying on a sword that hasn't been properly tempered or firing a handgun that's been fashioned out of untempered steel! The handgun wouldn't withstand the force of the bullet that it fires and the same is true for your techniques; your weapons must be able to withstand the force that you emit.
Temper your weapons! ~ Shifu Winkler