Out of curiosity, I recently ordered myself two of these handmade pieces. Mine have the large 95mm carbon steel blades that appear to have a very slight hollow grind on both sides. You can open Higonokamis with a single hand with some dexterity, but there is of course no hold-open mechanism whatsoever, so the tasks you can do with these is quite limited. I keep one of mine on my desk to open mail and packages and have gifted the other one to my brother. These can be bought off ebay directly from Japan for quite low prices. Many seem to need a little deburring and final honing or polishing of the edge.