A heavy bladed knife with at least a 5" blade is an absolutely essential and universally available tool. You may choose either a single or double-edged blade, according to your preference but be sure its sharp and tough.
When using a knife for sentry removal, approach the target from behind, grab his face and tilt it back. Simultaneously stab the knife into the side of his neck and push in forward. This will sever the arteries and wind pipe. Don't attempt to slash across the throat as this is a more awkward motion and is much less effective. A stabbing wound to a kidney is also very effective but may leave the target able to make quite a scene before dying. Approach the target from behind, grab the shoulder with one hand and stab the knife into the kidney area as deep as it will go with the other hand. Turn the knife sharply it and rip it out. This will leave a gapping wound which will be nearly impossible to close.
The US Army FM 21-150 offers several sentry removal techniques with the combat knife. These two are the most suitable for selective assassination:
Kidney Stab, Throat Cut:
This technique relies on a stab to the kidney to induce immediate shock. The kidney is relatively accessible and by inducing shock with such a stab, the operative has the time to cut the target's throat. The operative completes his stalk and stabs the kidney by pulling the target's balance backward and downward and inserts the knife upward against his weight. The target will possibly gasp at this point, but shock immediately follows. By using the target's body weight that is falling downward and turning, the operative executes a cut across the front of the throat. This completely severs the trachea and carotid arteries.
If it is necessary to strike the target from the front or if you are in a self-defense situation, keep the knife out of view until you plunge it into the enemy. Use a backhand grip and hide the knife behind your wrist. At the last instant flip it to a front grip and thrust it upwards dead-center into the solar plexus. Pull it down and turn it as you rip it out. The target's guts will spill out along with copious amounts of blood. He will make very little sound if any but you will be soaked with blood.
An icepick or a similar thrust-only type weapon can be used to produce wounds which will bleed much less than those inflicted by a knife. This is a definite advantage for selective assassination where the operative must make a getaway without being spotted with bloodsoaked clothes. The wounds are, however, not nearly as lethal as those produced by a knife. The kidney attack can be made with an icepick but a direct thrust into the heart or brain will be more likely to produce a fatal wound.
A hammer can be used to produce lethal injuries silently and almost completely bloodlessly. A very hard blow to the head with a standard claw-hammer its almost certain to kill, a follow up blow or two will certainly do the trick. Again an attack from behind will be most effective, strike as hard as you can.
A thin length of strong rope, cod, or even a belt can be used to make a garrote which can be used from behind for silent and bloodless killing. Loops or handles are often added to the garrote in order to increase the effectiveness of the attack. Surprise is absolutely imperative when using one of these weapons.
(For Information Purposes Only)