I am sure you can end someone's life with a curse if you are advanced enough and dedicate the time and murderous intent towards them, but I personally find death too merciful. I would much rather curse someone to get exactly what they did back, for example if they make you break up with someone, I would curse them to have all of their relationships failing miserably for the amount of time that took me to get over the break up. But you know your situation, if they tried to harm you and you are in danger, you do what you gotta do.