Nice piece. First of all, if I am seeing the pic right, it looks like it says W C Kelly - which helps to date the piece. The WC Kelly is the logo and imprint that some of the original Kelly axes had on them. While yours is not in pristine condition per se, it is still a nice piece. And the WC helps to give it a rough time frame, but it is hard to absolutely tell because the name was used even after the old man passed on. The fact that it says Charleston on it atleast dates it to post 1904 though.
What I would do, and this is just an average joes 2 cents, is I would clean it up. I wouldnt mess with the poll and trying to even it up, you might end up hurting the imprint, which you dont want to do in this case. I would try and shine up the face, and I would probably replace the handle. Getting those nails out is always interesting, but you should be able to do it. Then I would put it on the wall somewhere. I wouldnt use that for getting roots out, unless you really wanted to.