The first step in identifying French provincial silver is determining where it was assayed. In this case, the helmet should have a number on it: that number will correspond to the number of the Département in which the piece was assayed. Here's an example:

Here, the number "27" indicates the Dyle département, which no longer exists; it was one of the foreign territories annexed by Napoleon during the Empire, now part of modern-day Belgium. It's primary assay office was in Brussels, which was operational under French jurisdiction 22 Oct 1798 to 14 Dec 1813.
Can you make out the number? Once you've identified that, I'll see if I have the appropriate reference book.