Qapla'! I’ve made a Klingon blade! It’s made of plywood, cut to shape with a jigsaw, and sanded and painted ad nauseum. The straps are scrap leather I had lying around. You can cut shapes like this by patterning from the show (adjusting the size if necessary if, like me, you are not Klingon-height), tracing onto plywood, and CAREFULLY cutting with a jigsaw or coping saw.
I really wanted to make it out of metal, but it turns out those are illegal in a lot of the U.S. It’s the same reason I made sure to leave some of the wood grain showing and not sand the edges down to too much of a point. Metallic paint works well as a substitute for the metal, though.