Hey Detlef,
I tried to find if there where any past threads on this one...thought there where but maybe it was just some discussions before I remember???
I don't know the name for these, but they are a nice style of utility knife you will find in Thailand, and neighboring countries. You might commonly hear about it called a rattan splitter. The long curved handle is functional because you can use your forearm, knee, stomach it to brace/stabilize the blade which allows you to do either a push or draw cut
Here are some other examples: