Assassins are skilled in piercing their enemies. They are doing it very well. So this skill is another piercing skill. You need a piercing weapon , sword or dagger to jab your enemy, but when you have one , you can do incredible damage with it. Damage of the jab highly depends on the weapon which you are using.

See also: in-mud help for pierce, in-mud help for enemy", powerstab, arterial attack