Assorted critique:

Why is she standing on her tippy-toes?

The pose looks off-balance, like she'll fall to the left and backward.

Her upper arms are too short, and this makes the whole arms too short. The lower arms are fine.

Her upper chest area (breasts, armpit, clavicles) seems disproportionately small. Grab some ref, especially for the armpit area. There's flesh that makes the arms smoothly transition into the chest that seems to be missing in your sketch.

AFAIK the Darkest Dungeon sprites aren't vector, just high-res raster art that's scaled down as needed.

I agree overall though, pixel art seems like a lot of extra work for no benefit at this size. High-res raster or vector art would probably be easier to work with and more flexible in this case.

The character still looks off-balance to me, although in a different way this time - they look like they'll fall backwards. I think it's because the knee is slightly too high up, making it look like the leg is bent a little (the thigh looks foreshortened). The shading might also play into it, and I'm sure the permanently tippy-toed look doesn't help with making the knee's apparent position. There's a lot of subtle stuff that comes into play at large scales like this xP

I don't have a solid suggestion for remedying the balance issue, but I'd probably shade the shin to make it look like it's not coming forward at the viewer, but it rather going slightly back, as it does in a natural/relaxed pose.

You're right that the hands are too small. Hands, from the bottom of the palm to the tip of the middle finger, are usually about the same length as the face from the chin to the natural hairline, perhaps that can help you get the size right? In your case, you've got the fingers sized correctly as far as I can tell, the palms are just too small. The palm is usually about the same length as the fingers (it varies between individuals, sometimes it's shorter, sometimes it's longer).