A blade-opening arrowhead or broadhead that has one or more blades each pivotally or otherwise movably mounted with respect to a body or a ferrule. Each blade is moveable between a closed position and an open position, for example to increase a cutting diameter of the arrowhead. An actuator or an activation arm can be used to operate a cam surface. The blade can move as a follower element in response to movement of the cam surface. In the open position, the cam surface can contact the blade.