How to restore a baseball bat for autographs?

I have a game-used baseball bat that I want to get autographed next year at a minor league baseball game. The bat does not have any cracks in it but it is worn and has a few small dents. If the bat is autographed on the bare wood where it is worn, the autographs will fade after some time. I want to use polyurethane to coat the bat so the autographs won’t fade but I am not sure if the coating will come out bumpy or damage the bat. Is there someone who is familiar with how a baseball bat is made who can give me expert advice on whether or not polyurethane is the best way to coat the bat? Is there also a paint I can use that will be safe for the bat and come out OK?