The balance point isn't always 9.75" from the button for all violins, I don't think!
I'm a player, not a maker, and I go by feel. I think actual weight is important, but overall balance more so. When picking a bow, I just get a feel of the balance when I pick it up, and feel how it responds when I play. Some heavier bows actually feel better balanced and lighter in the hand than some lighter ones, some don't. I don't know why, it just does!!! If it's too heavy, I ask for the winding to be changed to plastic, if it's too light to silver, and try it again.