I'm coming to this discussion late, but for whatever it's worth to hear, I've been in agreement with Taz42o and CC Hunter about these objects for many years -- parasol/umbrella-top finials.
Pen-holder is a reasonable guess based on the general shape... but as the photos show, there needs to be an "attachment" hole or similar attachment provision on the small end of the pen-holder's tubular body. The parasol/umbrella-top finials have no such thing there.