Interesting designs you've got going there! The first one reminds me a bit of a mix between Newground's
Madness-series and
Zardonic. I think a more aggressive stance would work quite well with that guy!
As for the chain-guy, try making details such as the chain links a bit thicker so that they remain visible in a scaled down version. It's fine to ditch reality for that, keep all parts of the links the same width. That way, the bottom half doesn't become invisible/hard to see.
Our friendly skull-dagger-wielder might have trouble seeing, though! His eyes are
really far apart, almost giving him a bug-like appearance. Not sure if you intentionally went for that but it seems kind of odd.
Good sprites, though! Some technical aspects can be improved but they do convey the ideas behind!