At its twenty-seventh session the designated the O-Horidashi Sadamune, a of the Kyoho -cho whose name records that Tokugawa Ieyasu discovered it at Fushimi; Ieyasu gave it to Maeda Toshitsune in Genna 2 (1616). Its maker, Sadamune, called Hikoshiro (彦四郎), was the pupil of Masamune and by tradition later his adopted son, by some records his son, and succeeded him as the second generation of the mainline, working from the very end of into early . The published sources repeat that for him "no certain signed work exists at all" (確実な在銘の作は皆無): the entire oeuvre is , settled by and attribution inscriptions and by , and his manner is known by triangulation, for "what bridges Masamune and is Sadamune" (正宗と信国の間をつなぐものが貞宗).
The line against the master is qualitative and constant. In nearly half of his designation texts the states the standing formula that "compared with Masamune, his appeal lies on the whole in a calm, relaxed notare-based " (正宗に比較すると総じて穏やかでおっとりした湾れ調の乱れ刃に持味があり). One text details the contrast: the forging somewhat calmer than Masamune's, the standing less, the sparser, the workings of and somewhat scarcer and quieter. His own positive signature is the chisel. He is the carving master of : , , , and recur far beyond anything on Masamune, Yukimitsu or Norishige, and "the twin grooves were a specialty of Sadamune" (二筋樋は貞宗の得意としたところ), cut on and alike, a being named Sadamune for them. The published sources add that the is precisely what was not seen in Masamune: his carving "follows the line of Daishinbo, excelling in , the layered relief carving, which he passed to his pupil " (大進坊の流れを汲んで、重ね彫を得意とし、これを弟子の信国に伝えて).
The is an mixing , on the finest pieces kneaded close and minutely covered in , with entering finely and incessantly, at times with a slightly standing tendency. Over it the runs as a shallow mixing , and , and entering, the deep, the thick, bright and clear, and working through the , and at the ; the is or with and , often with a pointed tendency. The texts name as the mark of his "the beautifully shining peculiar to the top rank of - work" (相州伝上位作特有の光美しい沸). Around this mainstream two poles stand. " is rare" (直刃は稀) in him: the few quiet pieces carry a with shallow feeling and spaced wide, and a in this manner is said to recall the Fushimi Sadamune. At the livelier pole the grows prominent, rough mixes in places, and scatter and the sweeps up in flame-like ; a few works show a -like feeling, yet the texts measure the limit exactly, "never going so far as Hiromitsu and Akihiro" (広光・秋広までには至らない).
His divides into two types for and alike, and the dates each blade by which build it shows. The earlier keeps the -end style the texts call old-fashioned (古調): blades of ordinary width with , and small with little or no , the smallest of them likened to the Sadamune. The later is the grand build that carries most of the surviving work: of wide with little taper and an extended point, and wide and of thin , very often . On the pieces the itself is a tell, with a -form tip and , called "exactly the rule of Sadamune" (貞宗の掟通り). Kata- was a construction he favored, the celebrated example being the Sadamune handed down in the Kishu Tokugawa family as the sword of its first lord Yorinobu. Old -period papers are sometimes corrected at designation: blades papered to Takagi Sadamune or to Yukimitsu have been re-judged as Sadamune.
Among Masamune's students the published sources call him the one who carries the master's manner most faithfully, his skill next to the master's; at the top of his range the boundary runs against Masamune himself. Of a Bijutsuhin formerly of Ikeda Nakahiro, Honma Junji remarked that the shows more variation than the usual work, a flame-like and brilliant , and that he "would rather see it as Masamune" (むしろ、正宗と見たいものである). Downstream the triangulation holds: his gentler and his are exactly what reappear in , and it is through Sadamune that the carving tradition passes to that pupil and his line.
Fujishiro rates him Sai-jo , and eighty-seven designated works stand on record: four National Treasures, twelve Important Cultural Properties, two prewar Bijutsuhin, twenty-three and forty-six , sixty-nine blades in the two upper tiers together. The carried by his attributions are many. Beside the O-Horidashi stand the , the Zentokuin given by the shogun Hidetada to Maeda Toshinaga, the Ujiie of the Kyoho -cho, the , the , and the Shishi Sadamune, a treasured sword of Toyotomi Hideyoshi burned in the fall of Osaka and retempered by the first-generation Yasutsugu. Forty-one blades carry recorded provenance: one is recorded as presented by the shogun Ienobu and worn by Ietsugu, another was given by Tsunayoshi to Yanagisawa Yoshisato in Genroku 10 (1697), and transmissions run through the Owari and Kishu Tokugawa, Maeda, Date, Mori, Ikeda, Satake, Hachisuka and Takatsukasa houses. For the collector very little of this can ever trade. The National Treasures and Important Cultural Properties are patrimony outside the market, and recorded examples rest in the Tokyo National Museum, the Tokugawa Art Museum, the Mitsui Memorial Museum and the Sano Art Museum. What can realistically be met is the and tier, sixty-nine blades, nearly all or resting on attributions; such a blade comes to market only rarely, and a piece carrying the twin grooves or the layered relief carving, the chisel his master never showed, is an event when it does.