Dear Edward
Your rather fine tsuba is inscribed, as you correctly say, HIKONE (NO)JU TSUNEMASA. Neither Bamen Tsumasa nor Gotō Tsunema used this combination of kanji to sign their work, but Haynes lists eight artists who did so. None of these are shown as including in their mei Hikone, in the Shiga prefecture, as their place of work, and your tsuba cannot be considered to be Hikone-bori.
Of Haynes eight artists, the most probable one is H 10837.0. He is described as working in Sendai in the Mitsu province, and as working in soft metal plate in the kinkō style. But what this artist’s connection is with Hikone I do not know, and your tsuba may be by another artist of this name.
Kind regards, John L.