I think his legs look pretty good, only his arms are really weird. people usually bend their elbows and stuff. Im pretty sure you can find tons of ref material for this animation online.

Everyone above me already has said a lot of good stuff, I just want to add my thoughts. Low amount of colours isn't just used to make something look retro, it's just that a high amount of colours is really difficult to manage, especially with animation it makes everything much harder. 32 made a good pint that with a low colour count, it's much easier to focus on the fundamentals, I think thats the main thing.

Why do we use multiple colours? To discern certain parts of a sprite, to create shadows, and for anti-aliasing, is what i would say.
Let's now look at a color wheel created by http://gamecolorwheel.tumblr.com/.


You can see that there were basically only 4 colours used for discerning part of the sprite: orange for the skin, blue for the largest parts of clothing, grey for the weapon and purple for details. So with 4 colours, this sprite could already be done. This is reason #1 why a low colour count is pretty good, you don't need a lot of colours to create a good looking sprite. Also the other way around: more colours would make the sprite less recognisable. Those other 2 types adding colours, shading and anti-aliasing, is bonus. After you have perfected the fundamentals, you can add those, and you can add as many colours as you like.


What im trying to show is that low colour count isn't something specific to pixel art. Its a fundamental part of drawing in general. It is not because I think all pixel art should be like NES sprites and have only 3 colours. It's because a sprite's palette is supposed to have some unification. For example, when a character has a red hat and red shoes, by making them the same colour red, the character feels more cohesive.

I think schwee has a good point, on the butler guy especially it can read like his white sleeves have been ripped.

Dithering is a technique that should almost never be used anymore. Only if you go pretty high-res or for textures you should use it.
So for example on a stone some dithering would make it look rough. Id advice to stay away from dithering for as long as possible.

I couldn't find much examples from HLD, but assuming that it's just a normal top down game, that means you have to animate an attack in 3 perspectives, from the front, back and the side. If the attack is asymmetric you will have to make a 2 side animations, for example when a sword is in your left hand.

How many frames something has is really not set. That totally depends on how many frames are required and how many the dev actually wants. Since more frames = smoother animation (this doesn't mean more frames is always better).

For your 360 degree rotation you should rotate the sprite of the weapon by code, probably. Maybe look at Enter the Gungeon and Nuclear Throne for how they do that.