This is the 10 year anniversary patch for the First Imperial Stormtrooper Detachment.
The patch is shaped like a shield, like the regular FISD patch. The text on top says “10th Anniversary” in white Aurebesh letters.
The shield is split down the middle. On the left we see half of an Imperial Stormtrooper and on the right we see half of a First Order Stormtrooper.