My older brother gave me a Bible for Christmas when we were kids. He signed it and I still have it. Most bibles have a dedication page for this purpose.
If Huckabee were GIVING away bibles and signing them, that’s a dedication.
If he’s signing bibles people bring in, that’s an AUTOGRAPH.
I know for a fact that a certain segment of out Christian brothers and sisters collect autographs in their well used and well marked up Bibles, from preacher / evangelist superstars