Yes, its true! Yawara-jutsu is one of the old Japanese martial arts. One of its facets includes the use of a short, six-inch plain stick to strike death and terror into the opponent.
The experts will claim that it is used to jab kyusho or Dim Mak points resulting in severe shock to the system. This is only partly true. One hits vulnerable areas, it is true, but these are not necessarily surface vital points. They overlie deep nerves or organs which, if hit effectively, result in shock and bodily collapse. The same effect (almost) as when a footballer is accidentally kicked in the groin.
The stick can be held as a hammer, smacking down into a surface bone like the wrist. Or it can be flicked in a back-hand motion into say the teeth or the eye. Short and sharp somewhat like cracking a whip.
Probably its best use perhaps is holding at the middle, stabbing down like a knife into the neck or other target. Conversely it can stab upwards into the under-jaw. If then it is ripped forwards it could hopefully dislocate the jaw.
A more skilled use is in come-along holds and bone or joint breaks. But this is advanced technical studies requiring much (much!)...