Those metals don’t sharpen to even a workable edge, so no one would make knives out of them for the same basic reason they don’t make airplanes out of lead. You would have to start calling around to metal shops and see what they would charge to custom-fabricate something that looks like a knife made of copper or bronze. I don’t know if you’ll want to pay for something like that though, it’s not cheap. If money’s no object though, then you could easily approach any number of custom knife makers and see what they would want to whip up a knife made of copper or bronze. Like I said, it won’t take or hold an edge worth a damn and it can’t really be used, but what they present you with might be a serious art piece. Look around on Etsy as well ... people create all manner of things on that site. You might be able to find a custom knife maker there. Or just Google custom knives.