What do grenades symbolize in the novel, Grenade?

Grenades are symbolic of the violence being meted out by the opposing forces in the battle that takes place in Okinawa. It is significant that Hideki and the other boys are given two grenades with instructions to use one to kill as many Americans as possible and the second to kill themselves. Hideki only deploys one of his grenades, killing Ray and injuring himself. He leaves the second behind when he is approaching the America troops, knowing it will be seen as a threat and will get him killed.