While I didn't put it that way, that's not the worst summary. Though I would say whatever induced his narcissistic personality disorder made him weak, and his disorder made him cruel. Lack of empathy and the inability to reflect are not strengths.

Hitler came back from WW1 with the same rank he went in, which was a huge disappointment for him, then he failed as an artist and ended up in homeless shelter where he was disliked because, well, I guess he just wasn't very lovable or interesting. He was driven by resentment and a feeling of inferiority, which is narcissism 101, as is the fact that he put on a great show which he and others fell for.

Generally, even when "just" talking about a sociopath desire for power and less about the self-destruction of someone as sick as Hitler: any leash transforms people on both ends, and the very desire to have power over others betrays a lack of inner strength and integrity. I can't prove that, but I'll claim it. And furthermore I think people pretend to themselves and each other that power is an end in and of itself, because they're so scared of what it covers up. When you walk on a landmine, you can't just go on pretending you still have legs -- not so with abuse, trauma and neglect resulting in a haywire personality development, where routing around things, in ourselves and others, is often our default reaction.

P.S. If you're really interested in the psychology of Hitler as well as the Nazis historically I can recommend the books by Sebastian Haffner, the titles make it kind of obvious which ones apply.