Assassins are known for their knowledge of the weak places, that their enemies could have. This skill is first, it\'s just basic knowledge of such places. Because they now know where to hit their enemy, damage that is made to him is quite much better, especialy when you are backstabing.This skill works properly only on living humanoids, cause here is specialization of assassins. Put simply, assassin knows how to hit the places that are critical for sustaining life, like heart, kidneys, arteries, important tendons etc.