[quote=LeeRoy]
What the heck are you talking about? Vibration is a repeated pattern of movement and resonance, a jackhammer is the premier example of vibration utilized in a tool. Apply the same concept to a weapon and it would work the exact same way because the only thing it would be used against is flesh.
[/quote]

... armor.

Also, Let's take a hypothetical weapon that emits a high frequency vibration. And No, Jackhammer is not a vibrating tool. It uses a distinct pattern, at a distinct speed to successfully break apart something. This pattern is simply an up and down motion. It is a controlled movement. Vibration is not a controlled movement. If applied to weaponry, could easily break said weapon if applied on some type of axis even. If not, and simply vibrates throughout, the damage to the user could be more so dangerous to the user over an extended period of time than the weapon would be to an opponent. Now, let's go into a strike. A simple strike may cause no more than a dent, perhaps similar to a blunt weapon, because while it may come on with a strong vibrating force, it is rather uncontrollable, and may move on it's own. Now, the only logical attack, would be one that was placed on another object for a longer period of time. Then, although very scattered, it would require a tremendous amount of force to place it and keep it there, not to mention an enemy striking with his own force back at you, and then, even at that point, the amount of force required to keep the vibration on an object would inevitably slow the object's vibration down. Then, do to a weak structure of said weapon, that vibrated all the time, because it could not possibly have a strong structure due to it's vibration, the opponent could easily place the needed pressure and break it. You might get lucky against some smaller blades.. but bigger blades will receive nothing more than momentary damage, before completely breaking your own.