The first generation of smiths who signed Sadayuki using these kanji was from Owari Province. He signed Etchu no Kami Minamoto Sadayuki or Etchu no Kami Minamoto Rai Sadayuki. On occasion, he signed as this wakizashi is signed, i.e. Etchu no Kami Fujiwara Sadayuki. He worked in Nagoya in Owari province around the Kanbun era. The second generation of smiths who signed this way was also from Owari but he moved to Musashi and worked around the Genroku era or 1688. He never signed with the characters, Minamoto or Rai in his mei. Based upon the style of signature, I believe that this sword was made by the second generation.
It is a strong wakizashi with a slightly wide mihaba. The cutting edge of this sword is 21 9/16 inches or 54.8 cm. The school of swordmaking was influenced by the well known Owari smith, Nobutaka. This blade clearly shows his influence. It has a hard jigane with areas of a coarse ko-mokume hada mixed with masame hada. There is masame hada in the shinogi-ji. The hamon is an irregular gunome midare mixed with ragged togari-ba. The boshi on the omote is ko-maru and nie kuzure while on the ura it is o-maru and almost ichimai. As noted above, it is signed Etchu no Kami Fujiwara Sadayuki. It comes with a silver wrapped habaki in an old shirasaya. The polish is old but servicable and all of the traits of this blade are clearly visible. It was awarded Tokubetsu Hozon papers by the NBTHK attesting to the validity of the signature and the high quality of the blade.