First of, welcome to Pixelation
I made a partial edit of your piece:
Some edits on the face/head, mainly the mouth which does not read well in yours as well as lowering the top of the hair. Always be aware of where the bones/the flesh are under the hair/cloth and so one. She would have a really weird headshape given how the hair is sitting in yours.
Edits on the armour to make it look less dithery. Dither can be helpful but very seldom is good at actually showing interesting texture. In some cases it can, but it is better at blending colours or using it with close colours to get a bit of subtle texture. If you want to actually have something like damage, dents and the like, I would not use dither for that.
And then the chainmail. You can see I did stuff like breaking a piece out and also giving it a bit of volume by haveing the rings be angled differently on the side.
Also a bit of AA stuff on the collar, If you got AA colours you can use, use them. Unless of course you plan to have a bunch of palette swaps of the same character, which does not seem to be the case here from how your palette is built.
There is some good stuff here, but there is lots that could overall be improved. For example the arms/hands do not look super convincing, especially the lower arm on the right side. The way you connected it up there with the chainmail and the inner line makes it look really flat and like she is made of some thing material that is just folded over at that point. Also any volume that you are trying to suggest with the different shading and highlights on the chainmail gets killed by the texture of the chainmail itself which does not follow any contours at all.
Also, some stuff about the design is weird. For one the sheath-belt being fixed to the main belt all the way on the other side of the hips instead of closer to the sword is super impractical and would be weird while walking. For stuff like this use reference. There is plenty of pictures around of more plausible ways to wear weapon belts and the like (Game of Thrones for example as well as of course actual photos of old armour and weaponry).
The combination of chestplate/chainmail and then leather trousers looks kinda weird and not very ceremonial at all.
Sitting down a bit and having unifying design elements throughout the whole dressup would go a long way of making it look more believable. For example you could have some design element on the chestplate which then gets repeated on the belt. In short, the top and bottom of the outfit do not really mesh all too well. Also putting chainmail into your trousers like a shirt would not really work, generally it would go over the trousers a bit and form a kind of skirt. Again, looking at reference will go a long way here.
The collar also has a weird slant to it and the shoulderguard on the right looks a lot smaller than the one on the left, but not enough to look intentional.
OK, this was quite a wordy critique, I hope it helps. I think it has potential if you spent some more time on it. Keep it up.
Also for a ceremonial armour you would probably want to have no wear at all (dither stuff you have on the chestplate) since it would not have seen combat.
