There are a few articles (Wikipedia; e.g.) on the Internet about a Hans v. Polenz, Landvogt in areas SE of Berlin (Upper & Lwr Lusatia). One of the articles has a drawing purporting to be his coat of arms; and, the shield bears this principle charge of an eagle's wing. However, the crest, in this example is a repeat of the principle charge on the shield (a common pattern in German heraldry).
This Hans v. Polenz is known to have aided my ancestors' gang of robber knights, in the early 15th C. His motives may have been more than simple desire to share in the booty and may have had something to do with his efforts to acquire the Landvogt position in Upper Lusatia.
Most of what we know of this activity comes from CODEX DIPLOMATICUS LUSATIAE SUPERIORES, a collection of xcribed records from Upper Lusatia, and many from its principal town, Goerlitz.