These issues should be dealt with at the airport - and if you were asked what follow up action you wanted taken, the magic words were "I want to press charges".

It was your responsibility to inform the cabin crew of the assault and threat and request the police meet the flight as you intended on pressing charges - if they refused, you should have dialed 9-1-1 after wheels-down and told the operator you were assaulted on board Delta flight xxx which was about to park at gate xx and you wanted the police to meet the flight before anyone deplaned.

If you never intended on pressing charges, I'm not sure what you're after at this point - Delta owes no compensation.

If you don't have any intention to press charges, then there is no use continuing to think about the matter. Anytime someone assaults you, it is your responsibility to document the assault and press charges so the person assaulting you can be dealt with.