Hi Arnon,
You'd probably have better luck posting this question in the toolshed (in the "General" section"). And to answer your question, yes, I have made a knife out of a reciprocating saw blade. I used to make knives out of all sorts of things when I was a kid and had access to a shop. A reciprocating saw blade is pretty thin for a knife, you won't be able to do much with it. Something somewhat sharp can definitely be made, though.