BJ,
Interesting notes on the 'dent' in the scabbard, and the idea of preventing the telltale rattle sounds plausible in some degree...whatever the case, interesting sword lore. To me it has always seemed that the unmistakeable sound of cavalry would be nearly impossible to mask, pounding hooves notwithstanding; the rattling of trappings and accoutrements etc.
There were of course also the covering of swords entirely in leather, in Mexico in the 19th c. to prevent the glint of shining steel in the sun. Actually more likely to prevent burning the hand with relentless desert heat and sunlight heating the steel to stovetop temperatures. This was done in WWI in Palestine and Mesopotamia with the British M1908 bowlguard cavalry sabres, whose huge bowls were entirely covered in leather.
I had one of these 'Allenby' swords (for the commanding general in those regions) once, a beautiful Wilkinson blade as well! It really was attractive (I love leather...and !...oh well
.
All the best,
Jim