This is very interesting. If I had aphantasia I would have to radically alter the way I draw and design, as I always visualize things like designs and animations in my head before I get to a paper or pen. Very often when I travel to work I use that dead time to visually imagine designs, moves my characters could do and stuff like that. Imagining something I'm drawing and rotating it in my mind has helped me a lot to solve problems while drawing.

As someone else said, though, these imaginations aren't 100% accurate and many times what I imagined doesn't completely work in paper, but it helps me greatly to get most of it down, and I feel I have gotten better at mentally visualizing stuff as I got better at drawing. I can't imagine how I would draw otherwise. Hell, most of my thinking is done as a "mental voice", I reason things by mentally talking to myself, so to speak. I rarely think things abstractly.

And I can imagine sounds very vividly too; too vividly sometimes. I can "play" themes I like in my head as if I was just selecting an mp3 in my pc, but oftentimes I struggle to make them stop and they just keep "playing in the background" if I don't actively make an effort (which often involves thinking in something else, my head is rarely without sound) to do so. That's probably something I should get checked, ha.

I suggest you download a book on human anatomy, such as Loomis Figure Drawing for all it's Worth. It'll help you get a better understanding of proportions and other basic stuff.

As for this sprite, the biggest problem is the lenght of her legs. Ideally legs should be around the same length of the upper body (torso+head), sometimes more, sometimes less depending on what you want to go for, but in this case the legs are much shorter, giving that "dwarf-ish" aspect to your sprite. Particularly in the case of a sexy woman, which is what I believe you are trying to do, legs should be long.

I'll try to do an edit later but that should give you something to work with on the meantime.

What kind of battle would he be taking part on? Is he a hand-to-hand fighter, an armored knight, a soldier?

Right now it doesn't really look like a battle stance, feels more as if he was about to jump. Some kind of guard pose with raised arms as mentioned would convey the feeling of battle better.

I have a glide for moving to the sides. For a neutral it would be a bit boring to have no wing movement IMO.

I have nothing to say except it looks great and cute.