After you have cleared bits of moss and detritous from the hand, you find that the stone can be cupped by the palm, but by no means fills it. If anything, whatever was originally held by the hand would seem to be much more elongated. Perhaps the pointing finger even supported something long held by the hand. A rod perhaps, maybe even the haft of a weapon, would be your best guess. Flakes of rust amongst the moss would tend to support this.
Close examination of the pointing finger also reveals a lighter patch of stone at it's base, perhaps where a ring once nestled. Maybe some unknown scavengers took booty from this piece of statuary in the past. How far in the past, who knows? Maybe a lair lurks nearby...or did so many years ago? If there was activity recently, perhaps there will be tracks.