Any really good survival knife can be used in order to improvise an expedient spear using it with a good stick, a cane or anything long and straight; you should use some wire or thin rope to fix all elements together.
In this case, Alberto Prat is showing the spear he made using his own knife as well as colihue cane and some parachute cords. He used this weapon shortly thereafter to successfully hunt for mice in the forest.
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