I think the flames add more interest into the whole piece and the sparks are pretty good but I recommend using more variety of sizes and also the the spacing could be more vary. For the armour, I think you just need to make the reflectivity of it more obvious and also add some chips and cracks to show that it has been used. For the brooch, I added more reflectivity and also make it so parts of it catches the light more. I am not to sure how it's attached but if you can find a 3D model reference, that should help you with the rendering more.

