Dust Devil: The Final Cut

Joe Niemand (John Matshikiza), a Sangoma near Spitzkoppe in Namibia, begins a tale that states "back in the first times, in the time of the red light, Desert Wind was a man like us. Until by mischance, he grew wings and flew like a bird. He became a hunter, and like a hawk, he flew to seek his prey. Taking refuge in those far corners of the world where magic still lingers. But having once been a man, so does he still suffer the passions of a man, flying in the rages sometimes, and throwing himself down like a child, to vent his wrath upon the earth. The people of the great Namib have another name for those violent winds that blow from nowhere. They call them Dust Devil's"A middle-aged man (Robert John Burke) walks on a road in the desert, and pulls over a car with a woman named Saarke (Terri Norton) driving in it, who takes him back to her house. while the two are making love, the man snaps Saarke's neck, killing her. Meanwhile in the town of Bethanie, Sgt. Ben Mukurob (Zakes Mokae) receives a phone call with strange voices speaking, as does Wendy Robinson (Chelsea Field) in Johannesburg, South Africa. In the morning, the man burns down Saarke's house, inside which he has drawn many strange symbols and pictographs. he then gets into Saarke's car and drives away. In Johannesburg, Wendy's husband Mark (Rufus Swart) accuses her of cheating on him, causing her to leave him and drive to Namibia. Meanwhile, Mukurob receives a call about Saarke's house and drives to investigate with his superior, Capt. Beyman (William Hootkins). Mukurob visits Dr. Leidzinger (Marianne Sägebrecht), who tells him that the incident may be a part of a strange witchcraft ritual.Wendy runs her car off the road and finds an abandoned camper (which Dust Devil had hitched a ride with at Bethanie) with a strange man, who she asks to help her push her car out of the sand. She then sees Dust Devil on the side of the road, and stops for him. Cpl. Dutoit (Russell Copley) and Cpl. Bates (Andre Odendaal) find the abandoned camper with dismembered body parts inside. Mukurob drives to Joe's home, the former Bethanie cinema, and asks him about the symbols that were in the house. He responds that it was the work of magic, to which Mukurob scoffs. Wendy and Dust Devil continue driving and pass another hitch-hiker, but Dust Devil tells Wendy not to stop. As they pass the hitch-hiker, Dust Devil disappears from the car.Beyman tells Mukurob that he has to take him off the case and hand it over to the U.N., but says that he can give any information to him. Wendy stops at a small motel for the night and tries to cut her wrists, as Dust Devil waits with a razor outside the bathroom door, but Wendy does not commit suicide. She goes to her car the next morning and finds Dust Devil inside, who tells her that she was asleep the day before.Meanwhile, Beyman gives Mukurob a pile of documented murders similar to the one he is following. Wendy and Dust Devil reach the Fish River canyon as Wendy's husband Mark, arrives in Namibia. Mukurob has another of his recurring nightmares and is visited by Joe, who tells him to go with him. Mark arrives in Bethanie and asks about Wendy, but is beaten up by some of the people at the bar. Joe takes Mukurob to a small mountain cave and tells him that the murders are the work of the "naghtloeper", a shape-shifting demon who seeks power over the material world through the ritual of murder. He draws the weak and the faithless to him, and sucks them dry. Joe explains that the naghtloeper must keep moving to work the ritual, but if he is tricked to step over a kerrie stick, he will be bound to one spot and his power can be taken. Joe then gives Mukurob a Kerrie and a sacred root to burn to prevent the naghtloeper from possessing him after it is killed.Wendy discovers human fingers among Dust Devils belongings and he tries to kill her, but Wendy knocks him out and escapes. Dust Devil then chases her and causes her car to crash, forcing Wendy to run across the desert. Meanwhile, Mukurob releases Mark from prison and together they search for Wendy. As they try to drive through a dust storm, Dust Devil attacks them, causing the car to flip over. Mukurob handcuffs Mark to the car and heads into the storm, telling him that he has a chance since the naghtloeper only takes those who have nothing to live for. Wendy reaches the abbandoned town of Kolmanskop where Mukurob finds her and searches for Dust Devil. He runs into Dust Devil, who stabs him. Wendy then finds Dust Devil and tries to shoot him but the gun jams. As Dust Devil walks toward her, Mukurob takes the kerrie and puts it in front of Dust Devil as he steps forward. Wendy picks up Mukurob's shotgun and kills Dust Devil as he says, "I love you, Wendy". Wendy then walks into the desert past Mark and the car, lays on the road and pulls over a fleet of army Casspirs.The film ends with Joe saying, "The desert knows her name now, he has stolen both her eyes. When she looks into a mirror, she will see his spirit like a shore blowing tatters around her shoulders in a haze. And beyond the dim horizon, a tapestry unfolding of the avenues of evil, and all of history set ablaze".

Question: The shape-shifting demon is bound to one spot when he steps over what powerful item?
Answer: kerrie stick