A one-hand operable telescopable knife assembly comprising an elongated outermost jacket enclosing an internal emission or containment chamber and an elongated knife blade assembly. A thumb stud is attached to and extends radially outwardly from the elongated knife blade assembly. The thumb stud extends slidingly through an elongated guide slot to permit a first locking notch to a second locking notch movement and control of the knife assembly contained within the outermost jacket. The first locking slot and the second locking slot are arranged at opposite ends of but are also arranged on the same side of the elongated guide slot. A transversely arranged slot on the blade assembly simultaneously lockingly engages a jacket locking tab at the second end of the outermost jacket upon rotation of the blade assembly by the thumb stud entering into the second locking slot on the side of the outermost jacket.

A self-defense apparatus is provided. The apparatus includes a sleeve sized to fit over an arm of a user, with a forearm portion, and an elbow portion. A housing is secured to the forearm portion. An opening is formed that leads into the housing. The opening is disposed near the elbow portion. A spike is disposed within the housing. The spike includes a first end having a point and a second end having a stop. The stop prevents the spike from fully exiting the housing. The present invention further includes a spring biasing the spike to be substantially outside of the housing through the opening. The apparatus includes a deployed position including the spike substantially outside of the housing, and a retracted position including the spike substantially within the housing.