I don't think any therapist would use terms of diagnosis unless they believed that person you're describing, has some of the traits or signs of being whatever term they've used. For me, murderous and psychopathic are absolutely correct and I know how lucky I am to be alive. It was a comfort having my T, having anyone for that matter especially a trained person who recognised and validated my suffering. I don't think it's unethical to do that, for all those years I believed being tortured was punishment for being badly behaved and I was finally told No, it wasn't you, you didn't deserve those things. It was him. That validation was a huge leap in the right direction for me.