Just so we're clear, I'm using "ethics" and "morality" as synonyms for each other and for "terminal values".

If you're settling a dispute, there's no objectively true meta-morality to go to in the same way as people speaking is the objectively there state of a language. One party wants some things, the other party wants other things, and depending on what the arbitrator wants, and how much power everyone involved has, the dispute will be settled in a certain way.

As for how you analyze your own ethics: You can't, as far as I know. The question of e.g. "do my actions reduce displeasure?" is only relevant once you've decided you want to reduce displeasure. We make decisions by measuring our actions' impact on reality and then measuring that against our values, but we've got nothing to measure our values against.