I have not seen a simple way of doing the type of Pass Merit Distinction style grading in Moodle. This is a very common type of grading in UK Vocational Courses where you cannot get a Merit unless you have all Pass criteria and you cannot get a Distinction untill you get all Pass and Merit criteria. You can read about it in an earlier Moodle discussion here
I have been playing with a modified version of the Rubric gradng system with modification for this type of grading (which I have called PMD for Pass Merit Distinction). I have made a short animation of how the interface might work.
Please post a reply here if this idea is of interest.