Blazon: Gules a bar wavy azure surmounted by two logs raguly palewise in fess argent
These may possibly be canting arms (“Stumpf” meaning “stump” in German), which also incorporate elements of the arms of the former municipalities of Weipertshofen (the fess wavy) and Rechenberg (gules and argent). I should note that this is all speculation.
Blazon: Per fess sable charged with a bar wavy azure, I per pale gules a tower or windowed of the second and of the third a Maltese cross argent, II of the second a wall of four towers of the fourth windowed and masoned of the first
The wall in the lower half of the arms presumably represents the local Roman observation tower. The town’s name derives from the sandy terrain (arenales) and its history with the Order of St. John, which is likely the source of the Maltese cross.