For Kol Nidre, Torah scrolls are removed from their cabinet and held at the reading table. I have heard people bless the people holding the scrolls with lange yaren, long years, i.e. a long life.
Similarly, on Simchas Tora, people walk/dance around the synagogue holding Torah scrolls. Again, I've heard people bless them with lange yaren.
Where does this come from and why is it done? (Obviously, it's always nice to bless people with long lives, but why is it done here specifically?)