One of the best flash games ever made

Yummers

that dual scythe is badass as hell

For most characters, even stickmen (unless there's a specific reason otherwise) the knee should be more in the middle of the leg, I'm assuming you're trying to make him look like he's in a kneeled position which doesn't really work in this case because the knee is too far up making him look less intimidating, along with that the back could arch a bit to go with the intended pose.
As for the head, you should make the ends of the bandanna a bit longer and maybe expand as they go outwards, as most fabric wrapped around something usually splays out a bit (example https://tinyurl.com/4bnsy69k)

The cleaver is quite good, though it could definitely be better, you should definitely play around with depth of objects, whenever you got the spare time practice making 3 dimensional shapes of all sorts of different kinds at all sorts of different angles, it will really help you out early. In this specific instance I think the cleaver getting larger at the top as it got closer to the viewer would make it much more intimidating and cool looking, Also, cleavers usually have the holes on the top right part of them, away from the handle. because if it was near the handle it would lessen its structural integrity and possibly break off later on in use. Its just easier to hang up on things in the top right area. The handle could be a bit smaller as well, Other parts about the cleaver in this specific instance are the blood splatter, the shading and the circle
For the blood, always make sure bladed weapons have blood connected to the actual sharp part, because as it stands he kinda just looks like he used it to hold some ketchup for his french fries, you gotta imagine how the weapon would enter a body and how the blood would pour out onto and around it.
As for the shading, I think you forgot to add some to the entirety of the right side, it kinda stops once it comes in contact with the blood. (also, the linework is a little bit inconsistent on the right side in comparison to everywhere else on the cleaver, though I'm guessing this is because you put the gray colour on top of it. If IbisPaint X has layers you should definitely play around with them to get that linework nice and crisp)
As for the circle its very clearly one of those shape tools, which would be fine normally but the linework that already exists kinda clashes with it.

Heres an example of an angled cleaver, though you could really play around with how its shaped and don't really need to be exact in terms of copying its size / angle
https://imgur.com/MALasMN

Also also also (also), blockade runners art uses a binary style aka aliased... or I guess anti-anti aliased lines and whatnot, which essentially means that when you zoom in close to their lines you will only see black and white (and other colours like red of course), an anti-aliased piece of art like the one you posted has transparent pixels that blend in to whatevers around it, which can be very useful for some things but.. (and this is almost purely out of yknow personal choice) using a similar style especially as a beginner in art is very helpful because if you look closely at certain parts of your piece there's some crispiness that is a bit weird looking.
Also, when making binary / aliased art the bucket tool is a lot more friendly to you

Hope this helps, if you have any questions about anything or what me to pick apart other pieces of art LMK