how do you get the one for killing a main target like a true assanin????? i've tryed with all of them but i still havent gotten it. beat the game in 4 days though.
im quite sure that acheivement is for killing a target with the hidden blade like you know you kill a gaurd thats killing well you get the point...
just try kill one of the boss's with the hidden blade.
u hav to kill him with the hidden blade without him knowing your there
This.
I did it in Acre with William. When he's in that little courtyard giving his men a talking to, climb up onto the roofs above him, up against the wall. After about 3 or 4 minutes, he will send his men away, at which point you can drop down behind him (slightly difficult, because he's close to the wall) and assassinate him for the achievement.