A hand-held, power-operated or power-assisted, crimping/er or decapping/er tool (60), for container closures, such as vial caps (C), has a hollow handle (50), housing a (pneumatic) piston-in-cylinder actuator (12, 13), with an external trigger (18) operating an internal control valve (16), to control connection of an external pressure supply, through an internal distribution block (11), and displacement of an actuator output rod (15), coupled, through a pivoted bell crank lever (10), to a demountable crimping/er or decapping/er (27).