Sentence:  As soon as Julia returned with a constable, Timothy, who was on the point of exhaustion, prepared to give over to him gratefully. The newcomer turned out to be a <WSD>powerful</WSD> youngster, fully trained and eager to help, and he stripped off his tunic at once. 
Meaning of the word marked with <WSD> tags:  Having, or capable of exerting power, potency or influence.