Poison dart
Poison darts are a new ranged weapon featured in Assassin's Creed: Brotherhood. This ability can be purchased from Leonardo da Vinci; he will, in turn, fashion a dart-enabling upgrade for the poison blade. They have the same effect as the poison blade, but are fired from distance in the same way as the hidden gun, making them extremely useful for stealth missions. However, firing a dart is silent and aiming is almost flawless, similar to the crossbow. Ammunition is shared with the poison blade, thus increasing the poison bag increases the number of poison darts the player can carry. Poison can be looted from dead guards, or purchased from Doctors.
When hit by a poison dart the target will first keep walking but act slightly ill until he draws his weapon and starts swinging it around. After this, the target will fall down and die. Usually guards will not notice when you shoot their partners with a dart but sometimes they will attack. Poisoning guards (especially the guards with long weapons) is a good distraction and will cause the near by guards to fail to stop you from using your hidden bades to silently assassinate them.