Here is a post apocalyptic sword I built today. The best way to make something look like it is good for a particular purpose, and made in a particular situation, is to have it actually be that. To that end, I used only scavenged materials, limited myself to only the TIG welder (the welds are very similar to oxy-acetylene torch welds), even though the MIG would have been easier for parts, and generally tried to keep everything in line with a "limited resources" kind of mindset. I also tried to come up with a good excuse for every part on the sword. Obviously aesthetics were important to me, but I did make sure that everything I welded on had a functional purpose. This was a good exercise in low resource engineering, and a pretty cool result.