Dying at the hands of your younger sister

Shera looked scornfully at the woman. "Why do you want to kill me?" Before the latter could respond, she added, "Don't flatter yourself. I only want to know the level of your stupidity. What makes you think that you can kill me?" 

Vivette's hand was getting weaker by the second. She was losing too much blood and knew that she would faint at any second. However, she knew that if Shera knew that she was on her last strength, she would take advantage of it. Hence, she merely spat out five words. "Because you deserve to die!" 

What right did Shera have to be better than her? In what way was she capable?! 

"Actually, you're right." Shera looked down at her like she was a piece of garbage. "One of us deserves to die, and that person isn't me."