While rank may be arbitrary it reflects something. From my limited experience with COMON tabletop standard 5 - is clearly not what you see on tabletops. It is somewhat comparable to what GW stuff uses for demonstration games for new customers - in other words it is very decent level of painting.
Now, a little bit about the theory of scoring

) Since COMON scores are integer numbers and assuming that your work does not causes intense love/hate we have to assume that most people score it at 6 and 7, with the minority at 5 and 8. Alternatively, you can get the same average with 25% of each from 5 to 8, but that would suggest love-hate situation

). So, in order to get 7 you have to convince a decent number of people that this work deserves 8.
Why this particular mini does not deserve 8 in my opinion. First several subjective reasons: 1) Quality of the photograph – has nothing to do with painting but it is the only way for people to judge.
2 ) Choice of the mini. There are literarily hundreds of ultramarine renditions out there. So the basis for comparison is vast and an ultramarine has to be truly amazing to stand out
Now, lets move to more objective problems:
3) Almost no highlights/shadows. The armor is pretty much flat. The cape is very flat. Banner pole too.
4) Straight metal. Something I have to repeat very often. There is no such thing is straight metal. Even a fully polished blade on a parade ground will reflect light unevenly therefore it will never be a flat “boltgun” metal color.
5) White parts (U on front, back and shoulder pad, some parts of a banner). It is very difficult to paint white because of the coverage issues. Even though, using thick concentrated white is not a solution. It becomes streaky, uneven and blotchy. To deal with this you might want to paint “future” white areas with light gray first and then put several layers of white slowly moving toward pure white.
6) Freehand. Just having it is insufficient, it has to be neat. Now it might be considered going too far, but remember, you want some 8 to get your 7. So... the cape. The black line separating gold and blue is of different thickness in different places; while it might be by design the reason for this is not apparent. Lettering is very uneven everywhere. Usually when I do something like this I first try it out several times on a flat surface to make sure I know how it all looks. Then, with paint that close to the base color (so I can easily overpaint it if I mess it up) I make a contour of my letters. At this point, since they are barely visible, I can change positions, size and appearance until I am satisfied. Then I work to brighter colors from there.