It is a weight for the Roman spear, the pilum, to increase shield penetrating mass. If you blow up the jpg picture here of the man second from the right, you can see 5 sided object below the iron head of the pilum. You can even see the 5 little balls. yup yup yup..
“Pila come in two models: heavy and light. Pictorial evidence suggests that some versions of the weapon were weighted by a lead ball to increase penetrative power, but archaeological specimens of that design variant are not (so far) known.[”
https://upload.wikimedia.org/wikipedia/commons/8/88/AdamclisiMetope27.jpg
https://en.wikipedia.org/wiki/Pilum#:~:text=The%20pilum%20(Latin%3A%20%5B%CB%88pi%CB%90%C9%AB%CA%8A%CC%83,long%20with%20a%20pyramidal%20head.
That’s a great catch! But I don’t see sufficient detail. It could still have been on the staff for the legionary standard though.
The Romans had a weird little trumpet-like gizmo they used on the end of a staff, and the cavalry charges were accompanied by a sort of train-like whistle that rose in volume with velocity. The noise alone struck fear into adversaries.
