Hone, as a verb, means to sharpen. (As a noun, it’s the tool that you use to do the sharpening.)
Home, as a verb, means to send something home. (As a noun, it’s … well, I shouldn’t have to tell you.)
So when you review and improve the points you want to make, you are honing your argument.
But maybe you aren’t that far along yet. Maybe you haven’t quite put your finger on what point you want to make. You are kind of circling around the idea and you feel like you are getting closer. You are homing in on it, just like a homing pigeon flying toward its coop.
What you are not doing is “honing in.” You can’t hone in. There is no such thing as honing in. If you’ve been trying to hone in, stop it right this minute.