Leather guard / Rainguard
The 'leather guard' or so-called 'rainguard' or 'sword collar', begins to appear in historical sources around year1220-1230. However, its heyday goes back to the 14th and 15th centuries. It comes in many forms (semicircular, triangular, rectangular and trapezoidal, open form and closed at the bottom like a sleeve, etc) and has several functions, most often made of leather, less commonly copper alloys o silver.
It is not an inherent part of the sword and is something like an optional accessory. The most probable functions of this element, in line with contemporary interpretation, are the protection of the scabbard entrance, separation in some fencing techniques when the fingers touch the blade as well as additional hand protection in cases where the opponent's blade slides down on the blade`s flat...
The leather guard was sometimes adorned, but most often it was a shapely piece of leather resembling a collar on a sword's crossguard.
Not many original examples have survived, but there are quite a lot of them if you look for museums and research studies/