Iron tsuba signed "Choshu Tomonobu". Tomonobu was part of the Nakai Choshu School family. According to "Choshu Tsuba" published by Iwakuni Museum he was a second son of Tomotsune and and brother of Tomoyuki. He was adopted by Kawasaki family and become a Samurai.
Signature on this tsuba is very different from all other Tomonobu signatures I was able to find. However craftsmanship is rather similar to the one from example I placed at the end of photo section. I do not know If this tsuba was made by Tomonobu, however it would be rather strange to fake his signature.
Made of iron with beautifully carved dragon.
Size: 75 mm x 71 mm x 4 mm
Made in Edo period.