This Tsuba is a copy of the very famous Musashi Tsuba. Known to have been used by Japan’s most famous swordsman, Miyamoto Musashi. It’s quite lightweight for a Katana Tsuba Guard and has the distinctive double loop design.
The word Saotome relates to a very well known armour makers from the late Muromachi Period into the late Edo Period. They also made many variety of tsuba including this Saotome Chrysanthemun Tsuba Guard.