Alright lets get started!
I talked to you a little in game about some of the art you've shown.
Your concepts are a great start, with practice and dedication you will improve beyond anything one could imagine.
Now before I begin,
please don't look at my edit/redesign as something you can't obtain yourself. There are many artists that I look up to and I strive to surpass them; this is what makes me get better.
Well let start with the basics!-You should never use the pure black < It is transparent in game.
-Build a strong structured outline before you consider coloring/shading it.
-When choosing colors it will vary, sometimes you will need strong contrast to pull out the best in it.
I highly recommend that you don't take the RGB scale and just lighten the color of your darkest.. it will give very sad results. (I always have around 3-4 shades per area;The metal of this sword is 4 colors. These shades could be of other colors: IG you base is a silver/blue you could have a dull yellow or teal-ish color to give it contrast and to pull from the other colors.)
You asked me to give you a palette for pixeling, and as I said I usually choose the colors as I progress through the piece.
As for shading, this will vary from what you are pixeling wither it be wood/metal or even leather, each technique for these will stray away from the others.
-Metal is all about find a point where you can pull the light to.
-Leather is quite flat and I usually don't use a highlight color.
-Wood is probably the hardest to achieve; My wood is much like my leather just with a bright highlight.
Now every artist will find a niche when they are learning, this will be a place where no matter what your are pixeling you will always be able to achieve a similar effect in the art.
Anyhow I am not really one for explaining rather then just offering CC and making my own renditions! I feel you have the ability to tap into your potential but it won't be a walk in the park, you have to be able to keep pushing yourself and trying new things.
I look forward to you progress, feel free to contact me in game if you want advise or various help.
-Nerah
-Mat