The years of war had brutalized him to the point where human suffering no longer moved him.

brutalized 是动词 brutalize 的过去分词形式。brutalize 由词根 brutal（残忍的）加上动词后缀 -ize 构成，意思是"使变得残忍、使麻木不仁"。在句中表示"被战争经历变得麻木"的状态。