Throw a Long Weapon, Heavy Weapon, and Smoke Bomb more than 10m at a guard.
This is a new Achievement/Trophy from The Da Vinci Disappearance DLC for Assassin’s Creed: Brotherhood
To do this you just need to throw any of these weapons 10 meters away from a guard. You can do it on top a building, or right behind the guards. Just make sure you are farther away for it to work.
The throwing of weapons is a new feature of this game. You just need to hold the attack button for a few seconds then release for the throw.
For the Long Weapon, you can use any long sword or spear. For Heavy Weapon, you can use a Bearded Axe. Just keep a good distance. Hold the attack button and release, and you’re done.
After doing all of these, you should earn a Bronze Trophy for PS3 or 10 Gamerscore Points for the XBOX 360.
You can watch the video here