The criteria used by all examiners in current graded exams has been outdated and I have said to my students all the time, an exam cannot recognize clearly whether a performance is just a pass, merit or distinction. Via a new mark form, all you have done can be given a precise reason which makes less unfairness.
When you are practicing a particular piece, please think about which you are good at or weak in. Please focus on all aspects and try to improve with objectives so that you can get the most in the exams.
Different aspects of musical playing in the new criteria:
Under pitch, piano students should face less difficulty than string students. However, students need to play right notes in the right time (Of course).
Students are required to play in correct tempo with correct rhythm. (And this is an essential element for sure.)
Students should produce a good tone quality and be able to identify whether it is the desired or intended tone color. This is a complicated question required many analyses which needs to be aided by your teacher.
The examiners are looking for the details of your music and phrasing. The details include dynamics, directions and articulations.
The criteria assesses whether you can take a full command of your instrument, the level of engagement with the music and quality of communication.
Pinkham & North (2013, March). Libretto, pp.8-9.