Try writing to him, go on his website, see if you can get an address, email and send a letter. Letters give that personal touch.



Explain your situation, that you dont want to sell it, but perhaps if you could just have a letter verifying if the stick was indeed signed by him, and Im sure he will oblige with a signature that you could compare it to.
If he thinks you are just looking for a fast buck and a certificate to shift the stick, he probably wont be as helpful, if he thinks you are a real fan who treasures this item then Im sure he'd help you out.