Blunt Arrows are a type of arrow and tool used from the Bow available at Garrett's disposal in Thief. Cheap and simply made, the blunt arrow breaks on impact and is designed to interact with the environment at a distance, such as hitting a switch, without wasting more expensive options. It costs only 1 gold to purchase.
They are excellent for simple distractions, thanks to their low cost. They lose their charm in predator playthroughs, as they deal very little damage.
Shooting a guard with this arrow will cause them to instantly jump to a yellow eye state, and will not cause a suspicion rating to be added (suspicion may be added from other guards in the area though, depending on distance).
Listed as "ShatterArrow" in the game file, near a deleted "HammerheadArrow".