The branch splitter is a specialist tool, part of our Japanese bonsai tool range from Kaneshin. It is one of those tools which cannot be substituted by something else when you need to make a particular sort of cut.
Branch splitters are used for splitting branches and trunks as the name suggests. Sometimes it is not possible to bend a branch or trunk due to its thickness and so by splitting the section where a bend is required you can make the bend possible. In time the split will simply heal over as the blades on the Kaneshin branch splitter is thin although strong. This use is the most common one for the branch splitter but there are many others.
These quality Kaneshin tools are shipped in a retail box with a certificate of authenticity.
Take a look at this video of the craftsman sharpening this tool.