Found this knife in my Grandmother's collection. None of us can figure out what the semi-circle shape and slots are for (see attached picture). Anyone have any ideas?
It is a multi-tool, which appear to have been given out as novelties. The bottle opener and serrated knife are obvious, the slits are there to act as a pot strainer, the semi-circle shape and flat surface allows you to hold it against the edge of a pot and pour out the liquid while keeping solid bits in. I found a few of them on Ebay, the good links (as of this answer) are:
Vintage Multi-Purpose Knife Bottle Opener Strainer Stainless Wood Handle Japan - Given the nature of Ebay I can't guarantee these links will be good for long
According to the inscriptions on some they were given out by a couple of different Farmer's Co-ops and a Drilling company...does yours have any writing on it?
...and here is a picture of a pot drainer (single purpose) as it would be used.