Per the Blue Book, Arminius revolvers were/are made by Weihrach in Mellrichstadt, Germany. IIRC, the name has been used by at least two German companies, and guns with that name have been imported into the U.S. since the 1920's, but there is no current importer.
The trade name came from the near-legendary German hero Arminius; Wikipedia says: "Arminius (also Armin, 18 BC/17 BC - 21 AD) was a chieftain of the Cherusci who defeated a Roman army in the Battle of the Teutoburg Forest." Some of the guns have plastic stocks with an idealized picture of Arminius.
Most Arminius guns are in small calibers, .22 or .32; they are of fair quality, but not, IMHO, anywhere as good as a Colt or S&W. Value on the .357 runs around $200+ in top condition, but purchase would not be advisable as there are no parts available..
Jim