I like to believe that the most unique thing about life and death is that they both are the most important part of our lives, and we have little or no control over them.
Even though we are able to give life through the process of reproduction, we really don't have absolute control over the process. Complications could occur and the process terminated. Life in my opinion has everything to do with nature, a force no one can control.
Death on the other hand is almost easy to be served. A life can be taking at any moment. This will mean that we actually to an extend have control of death, but in reality, it' far from that.
Death can come at any moment. You might have the power to take another life, but what about your very own life? It could be an accident or natural cause, anyways, death is still largely not controlled by us. No matter how careful we might be in attempt to keep on living, we eventually die at the end.
My point is, life and death are unique because it's almost completely out of our hands. Nature or some life and death God has all the powers to either give or take life at any moment without notice.