neat:
I have tried telling Moulton that Terraria upscales stuff to x2 and you have to downscale first if you wish to copy from the wiki.Esther
One thing I notice in these sprites is the presence of "Mixels". Try to stick to one pixel size only (so 1x1, 2x2, 4x4, but never multiple of these at the same time) as it looks a lot better.
I'd recommend only spriting in 1x1 pixel format, then upscaling when exporting to make it 2x2 or bigger, rather than trying to sprite directly in 2x2 or other sizes. If you absolutely have to (like when directly editing a Terraria sprite), turn on a grid feature (and if you're using Aseprite, combine it with turning off "pixel-perfect" on the brush and enabling Snap to Grid so the pixels are always lined up).