The White Bone Heart-locking Hairpin, as one of the famous magical artifacts of later generations, didn't have any fancy effects.
Its usage was very simple: after refining, one simply had to channel their True Yuan into it, aim at the target, and activate it, causing the hairpin to swiftly shoot out.
Unlike the Immortal Sword, this thing didn't require a cultivator to be distracted directing its flight; instead, it locked onto the target and followed it persistently.
If the opponent blocked with a Flying Sword or used a wide-ranging Taoism Method to attack, causing the tracking of the White Bone Heart-locking Hairpin to be interrupted, it would return to its user's side. But, if the target was too slow to defend, and got pierced by the hairpin, they were pretty much doomed—the hairpin not only sealed meridians and acupoints, preventing the flow of True Yuan, but unless the owner recalled it, it was basically impossible to remove with external force.