Sentence:  Proper ritual observance at any level of society <WSD>was</WSD> capable of generating power for use in the spirit world ; but naturally , the royal ritual , which provided unusual control over already supremely powerful divine spirits , was held responsible for regulating the universe and insuring the welfare of the kingdom . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)