While I do not do a lot of finials, I do use a product from http://www.rubberchucky.com that holds the tips of finials and reduced their vibration. This product has two sizes and each has its own bearings inside it. It is not made for pressure but just to secure (lightly) the tip of the finial.
Recently, a friend of mine (who is a drummer and suffers from arthritis), asked me to put finger groves into his drum sticks. To do this I used my lathe and the larger of the Rubber Chucky finial holders. Since the tips of the drum stick are coated in a plastic, I decided to use the finial holder in the tailstock. Unfortunately, I pushed the tip of the drum stick into the Rubber Chucky holder a bit too hard and it cracked. I notified the company and asked them if could purchase just the larger of the two chuckies. Dan, the owner, wrote me back almost immediately and said even though I purchased the product 3 years ago, he was sending me a new one of the larger chuckies free of charge. What a surprise!
I just thought I would pass along this information to fellow turners. You might want to look at their website.