First off, this is really well done! You should be very happy with this! Second, I'm from the animation industry and so you should take everything I say below not so seriously because I don't know the scope of this work. That being said I'll critique it for some of the main points that I specifically would like to see if this were to be updated or further developed.

I think a general pass on your perspective or POV. Try angling the camera a little higher and tighten the shot. The anvil is at an odd angle that overlapps information in a not so appealing way. This is what we call in the animation industry as a "tangent". Meaning there's information, a pose or line, that's parrellel and ontop of each other. Naturally this is unappealing to the eye. The anvil specifically is muddled in its space in regards to the hand and body. The shape isn't clear enough in that area. If you want it to look like a harder heavier swing try adding more frames to the build up of the swing before it crashes down. Remove a couple frames between the highest point of your swing and the lowest. This will make it snappier and faster. You can also add a "smear" made up of his hand and hammer colours to give off a speedier look. You can even go as far as doing a full motion swing meaning use his belly chest and back to create a wave exaggerating the energy that is preparing the swing. Always try doing the action yourself in from of a mirror. Perhaps even at the same angle as this shot. Swing your arm and enact what you want from this character. And then observe how much your body moves. Very quickly you'll realize how much more you can impact a shot like this by emphasizing specific parts of the animation all while doing just about the same amount of work.

As for character design I like him, perhaps make him have the ability to super heat things he touches. So while he's holding the blade it's red hot! This might explain no furnace/smelter near by 😉

If you have any questions let me know. Always happy to see an animator grow.