A system is provided for a turbine engine. The system includes a rotor assembly and a monitoring system. The rotor assembly includes a plurality of rotor blades connected to a shaft. The monitoring system includes a processing system. This processing system is adapted to receive blade data indicative of a rotational position of at least a first of the rotor blades. The processing system is also adapted to process shaft data with the blade data to provide torque data indicative of a torque to which at least a portion of the rotor assembly is being subjected, where the shaft data is indicative of a rotational position of the shaft.