It can be very difficult to identify items that were originally part of something larger.
You have speculated that this might be a military badge, but that was not my first thought. Because the item is curved, suggests that it was part of something else that was round (military badges tend to be flat). and secondly, because the shaft of the item is threaded would indicate that it was attached to a threaded bolt/sleeve (military pins are generally attached via a butterfly clutch or a tie tack). And lastly, I have seen something like this before but have been unsuccessful locating any photos of it.
Try searching the internet with the following keywords
- knob globe cane topper
- Umbrella parasol handle
- pool cue butt cap
- tap handle
Something along those lines might turn up something interesting. My memory was of a walking cane with a globe handle and a metal insignia attached to the very top. It would have been easy to unscrew this emblem and replace it with something else. I don't think that it was designed to be user customizable, but instead the store/museum could order the walking canes with a custom emblem.
As for the emblem itself, you may be right on target with your phrase 'hexagonal bastions' also known as 'Star Forts'. Perhaps a little research in that area might reveal a star fort in italy or a place name that starts with the letter 'I' and also has a museum or gift shop where such an item could be found.
Good luck with your research, and please let us know if you find anything definitive.
