The copper is just a thin layer over a central high carbon steel core which also is the entire cutting edge. The copper you see does NOT go through the blade. You see it because the bevel is ground at an angle and it exposes the copper. The blade is very strong and very functional.
Galvanic corrosion requires the presence of an electrolyte. Keep the knife clean and dry and it will last a lifetime. Think of it this way... steel will corrode much faster than copper will. Keep the carbon steel from rusting and the copper will be just fine.
Welding means melting the metals into each other or otherwise merging them. This is more like brazing under pressure. If you Google copper brazing, you'll see that the copper brazing bond is in excess of 70000 psi in tensile strength. You'll destroy the knife before you shear the layers apart.
I get that some people have watched a video and have learned that traditional damascus is not the same process we do today. "Damascus" has become the defacto term people relate to for both. Just know that the American Bladesmith Society, Master smiths, and Journeyman smiths (like this one), don't care to delineate the terms and will say "damascus" for both types. If we want to refer specifically to traditional damascus, we'd say "Wootz". There's no need to "correct" me in YouTube comments. Would you really "correct" a mastersmith in person, to their face? No. So don't be that guys who does it on the internet. It makes those individuals sound incredibly pretentious. Don't be that guy.