There is a one in 121 chance when zapping or engraving with a wand to wrest another charge out of the wand, yielding the message "You wrest one last charge from the worn-out wand." and providing you with one last bit of magic after which the wand crumbles to dust. It is most commonly cited in connection with wands of wishing, where one last wish can be immensely useful; it is nevertheless possible with any wand.
A cancelled wand cannot be wrested from, as the internal charge counter is set to -1 by the act of cancellation.
The usual technique associated with wresting is to #adjust the wand to the z inventory slot and holding down the z key to zap the wand repeatedly, greatly reducing the amount of real time and effort needed to extract the wrested charge. Be sure to pay attention to what's going on around you while you hold down the key, or you may end up dead without knowing what killed you. Ideally you'd quickly tap the z key instead of holding it.
84 zaps are needed for a 50% chance of success.
An alternative for non-directional wands such as wishing is to engrave with it while levitating, or to abort when prompted what text to engrave. Unsuccessful and canceled attempts to write do not consume a game turn, but do attempt to use the wand. This is bug C343-246. When levitating, if you adjust the wand to E and hold down that key you will get your wrest very quickly. This is safe because the "You wrest one last charge from the worn-out wand." message triggers a more prompt, and no turns are consumed in the process. This makes exploiting this bug much faster with levitation.
This bug, contrary to earlier reports, has not been fixed on NAO.
If you manage to wrest the last charge out of your wand while engraving, you get the message "You are not going to get anywhere trying to write in the dust (or frost, if trying to write on ice) with your dust."