His sentence was reduced from life imprisonment because he is older and the head of a large family, as well as (if I am interpreting it correctly) his "fury" showed that it was a real honor crime, a crime of passion and not just an ordinary murder.
One twist: Not only did he kill his daughter because of his suspicion that she was involved with a man who was not her husband, but he also thought that she was involved in giving intelligence to Israel!
I'm not sure if that was a factor in the light sentence, though.
