The Gunsmith can be bribed with Mod Components to buy armor and weapon mods. Such mods are a fantastic way to improve your build. The Warmind Cell mods, which operate in coordination with the Seventh Seraph arms, are the mods. You'll be able to set yourself up in the position in the game after buying the whole set of these. Outside of buying mods, Mod Components aren't very useful. To be clear, you would like to be in such a situation where you can't get the mod you want because you haven't enough parts.