The dagger shows how macbeth feels as he feels un sure wether to kill duncan or not. The knocking on the door after he kills duncan as he feels that god is comming to get him. Also tv wife shows how vunrble as he does what ever his wife wants to please her. When macbeth slays the many soldiers it prooves that macbeth is a blood thirsty killer but when it comes to killing duncan he is unable to do so only beacause his wife encourages him to kill him.