Hey!

Cool sprite you got there! If you want it to be more shinier, you should add a bit more contrast to it, so that the shine sticks out more. Basically make the base colour of it darker and then the lighter shine colour will stick out Otherwise if it's a light colour on another light colour it all blends together. And in the same way I think it could use some contrast on the handle too, to better make it all pop, so something like this maybe

Love the design of the guy, he looks like some street level wolverine.

I think the biggest issue on your small sprite is readability and consistency.
like you have broken outlines on a lot of places, which just makes it look dirty and unfinished, so probably best to just close them all up or remove all together.
The face is also pretty unreadable and the eyes look like theyre coming out of his head too much, like they're popped out for example. So I tried just using less single pixels on the face, and i think that makes it look more readable. I see you were trying to show that large smile he has on the small sprite, but It just makes it look unreadable for the most part, so I think it's better to exclude that from the small sprite. Not every detail needs to be visible. You can maybe show that in the ingame portraits and such. Also added a little outline for the necklace so it sticks out more, otherwise it just looked like a bit of random pixels. Well hope it's helpful anyway!

Think I have to agree with eishiya, the background looks sort of much more realistic than the foreground, so it looks a bit weird. I think most of the issue there is the very squarish tiles you have going on. Try rounding those corner tiles a bit and such. Make the tiles a bit more organic, using less straight lines etc. Especially in the back tiles. I mean since you dont interact with them and dont need a straight platform on any of them, you can just go wild with it.(Tried to include it a bit in the edit)


Also I think the characters kind of dont fit in with it all too. I think the best way to fix it would be to tweak the tileset a little. Maybe give it a slightly darker outline around it. Basically give the outline to everything that is a main foreground element and is interactable with in any way. And the grassy part of the tileset I feel is too brigh, you could show a little depth by leaving only the very top brighter and making the sides a bit darker sort of like in the quick edit I made here.

Good job overall on it though! I like the monster animation especially!

You got some very similar colours used on the texture of the ice(the lines). It makes it all look very blurry and kind of like jpg compression, especially coupled with the random water texture on the sides. I'd suggest increasing the contrast of those colours or removing the similar colours.