>>7562856 (pb)
It is just a mini "Mace of the United States House of Representatives" brooch.
The mace is an ancient symbol of the Power of Governance.
Her wearing it is a transparently narcissistic, "in-you-face" overcompensation for her own interior self-doubt and lack-of-confidence in her suitability to hold such a high position of authority.
That, and Nancy uses it to stir her cocktails, so it is functional, too.
Pic related.
https://www.usatoday.com/story/news/politics/2019/12/18/nancy-pelosi-sports-mace-republic-brooch-during-impeachment/2692460001/