Here's something that caught my eye. While browsing the pictures in the site mentioned above, this "fragment of a painting of the palace in Kielce (Poland) in the 1630s" had two hussars, who appear to be wearing sabres with typical boot-hilt, and cross-guard with
side-ring. It's not the best clarity, so the side-ring aspect is debatable.
Then I remembered that I had seen a sabre with a side-ring before... in this depiction of Nikola Zrinski (Ban of Croatia 1647-1664) from the Klebebände (Band 2) by Jacob von Sandrart (publisher) 17th century. At first I thought it was a fantasy design, but now I must reconsider my verdict.
https://commons.m.wikimedia.org/wiki...and_02_337.jpg