Originally Posted by Minty
You just have to be locked on to a guard. You can walk up to 4 guards (like at a Codex location), lock in to one with LT and then hold X to throw sand. Just make sure that you're far enough away that if you punch it doesnt land.
I got mine by having four guards chase me, run away with them, then turn around and threw a smoke bomb at them. Whilst they were knocked out, I moved back a few yards (still locked onto a guard), held X and then when the guards came round from the smoke, let them get closer and then threw the sand just before the first guard hit me with his weapon.
Im still not able to just throw sand at people if im not in combat and when i try to hold X while locked on i just punch them