To further differentiate between aristocrat and high noble, I think it would be nice if nobles could have aristocrats arrested/beaten just as they can with adventurers. I like the idea of these lesser nobles having to tread carefully around even the lowest of the high nobles. I also like the idea of high nobles having to be careful as to which families they offend and having the real ramifications of both play out in realm.
Not sure about beaten, but I agree about arrested. Beaten doesn't seem very appropriate for the caste.