In physics power is defined as dW/dT, that is the derivative of work taken with respect to time – or in plain English the amount of work done per unit of time.
This helps us to understand the conception of Power in the context of people and relationships. That is only ACTIONS have power and power only exists in COMMANDS. A person may have great influence, massive wealth, a prestigious title, or an army willing to obey – But none of these things can make that person powerful on their own, that person simultaneously must must COMMAND the instrument of their power to ACTION.
All personal power comes from this combination of instrument and command. That is it requires both a physical and a psychological component.
When the psychological component is missing we have only the trappings of power. Take for example a judge who firmly believes in interpreting the law, and the Constitution, as written – in his duties he carefully, intelligently, accurately, and fairly applies the highest laws of the land to his rulings. He is by all appearances a powerful man, but this is false – all the power is held by the writers of the law the judge is merely their instrument. An individual is only powerful to the extent to which they are imposing their own WILL on the world, all the physical power in the world is powerless if it has no will.