Hi Sara--

It's not even a regionalism. Clemens is referring to the large feather
ornaments that decorated some 19th-century military ceremonial uniforms.

For an example, pictures being worth words, see:
http://picasaweb.google.com/lh/view?q=hussar&psc=G&filter=1#5201018981043121026>

or type "hussar" in any search engine.

Your fellow translator,
Gerald