A mechanical broadhead arrowhead has moveable blades that deploy from a retracted in-flight configuration to an outward deployed configuration as the broadhead strikes the target. Once in the deployed configuration, the blades are locked to each other against the resistance of the target, but freely pivot about the ferrule. Accordingly, if one blade strikes an obstruction such as a solid bone, the blade assembly simply pivots out of the way without damaging the blade, deflecting the trajectory of the arrow, or halting its penetration into the target.