This is just a very simple mod that replaces the Knife Knapping recipes. I discovered that if you fit two of them in opposite directions, they're the perfect size that the blades can be separated, and then there's just enough room to fit a third blade.

Now I find it far less frustrating if the stone knives feel a bit too weak, since early game involves so many of them. But to get an extra one helps a lot, because if you're not knapping knives so often, having to knap other tools won't feel as much of an interruption. Now you can use all that time you save on knapping for napping.