you should think more about how light operates in your work. here, for example, we see strong gradients on every part of the body. but working from a light source, we see which areas are darker or lighter depends on their relationship to the light source. also try not to rely too heavily on black outlines. they can help you build the picture but you shouldn't let them restrict what you're able to create.
That's an improvement, but you can do better. Check some knight armor references. Pay attention to the relative sizes of each part. Pay special attention to the helmet: the holes are there so the knight can see through. You covered those in your armor for some reason, with some unknown part (which also looks flat shaded). That doesn't make any sense. :(
The feet and the shield, especially the shield, are too small. Knights use big shields, and that one just looks wrong as it is.
My biggest advice to you is this: study and pay attention to the relative sizes of objects and body parts. This is extremely important for making any convincing piece of art. If one thing is too big or too small, it will immediately look weird to everyone. You've been making this mistake a lot, and it's something easy to fix with practice, as long as you pay special attention to it.
Keep practicing!