Why does macbeth brag that i smile at swords laugh scornfully at weapons'? what makes him certain he will not be killed?

wheres the passage with the idiom underlined

the tale of “aunty misery” written by judith ortiz cofer , is a folk tale about an old woman who earns immortality by tricking death . the cost of immortality however, is that her life will stay the same. from this tale it becomes clear that death is a necessary evil and is inevitable in life.  

question: which theme is found in the tale of "aunty misery? ”

answer: a. death may not seem friendly, but he should be treated kindly.