Sentence:  Secondly , to find a learned diversion and a pleasing joke in More 's account of the stupid brutalities of early sixteenth century wars , of the anguish of the poor and dispossessed , of the insolence and cruelty of the rich and <WSD>powerful</WSD> requires a callousness toward suffering and sin that would be surprising in a moral imbecile and most surprising in More himself . 
Meaning of the word marked with <WSD> tags:  having great power or force or potency or effect