This type of short civilian sword was known as a hanger, because it hung from the belt. Such swords were very fashionable in England in the 16th and 17th centuries. They usually had short, curved blades and were widely carried when travelling or hunting. Examples are often fitted with a distinctive staghorn grip.
Materials & Making
This sword was almost certainly made by one of the German cutlers from Solingen, who settled in Hounslow (now in Greater London) around 1629 and started a sword-making factory. The unusual cap and scroll pommel (knob) is very characteristic of Hounslow work. As with many London-made hilts (handles), the ornament consists of a 'dot and trellis' overlay in silver on a ground of artificially darkened steel. This type of hilt was fashionable from about 1635 until just after the Civil War of 1642-1646.
The blade was imported from Solingen, Germany, a celebrated blade producing centre. Solingen cutlers used the orb and cross mark. Some cutlers also used numbers or dates, as in this case, 1551. This is not the date of manufacture. It is probably the date when the family of cutlers who made the blade first established themselves.