Reizei Sadamori worked in during the period, and the firmest anchor for his name is a single small , signed and dated on the tang "Chikushu Reizei Sadamori, a day in the first month of Shohei 25" (筑州冷泉貞盛 正平廿五一月日), that is, the year 1370. The published sources return to this one blade in nearly every entry on the smith, because signed work by him is so rare that the dated has become the touchstone against which every other attribution is measured. They place him within the Kongobyoe line, traced back to the first-generation Kongobyoe Moritaka, and set him beside the school as the second of the two groups then forging in the province. What separates his line from the more famous school, the published sources say, is temperament: his is read as a Yamato hand carried into Kyushu steel.
The greater part of his record is not signed at all. It consists of , broad of body, thin in the , with an extended , the shape of a long blade cut down and judged to his hand. Over these the is an that flows and leans toward , especially toward the edge, the grain standing, with adhering thickly and entering frequently; the steel takes a clouded, blackish , and a faint whitish stands in the surface. Over that he tempers a low, narrow , the tight, with , fine , and a tendency to near the , and running thinly within. The goes straight to a small with at the point, at times finishing in . This restrained, austere manner, not flamboyance, is the published sources' named point of interest in his work.
The is the constant of the attribution. The flowing, -inclined steel, the standing grain, the dark and the whitish recur on blade after blade, and it is from these that the judges read his Yamato temperament. The published commentary calls the Kyushu coloration strongly present in his work, describing one as a richly flavored piece "in which the coloration characteristic of Kyushu swords is strongly expressed" (九州物の色彩が色濃く表示されており). The sources are candid about the difficulty of the reading: on one shortened blade they note that such Yamato features also appear in works like , yet conclude that "from the standing texture of the , the appraisal to Reizei Sadamori is the superior one" (肌立った地がねから、 冷泉貞盛の鑑定は一段とまさるものがある). The narrow and the dark, standing together carry the name where no signature remains.
Against this quiet standard stand his few signed blades, which break the pattern. The signed "Reizei Sadamori, resident of Chikushu" and the signed simply "Sadamori" abandon the narrow for a mixed with and , wider in the temper, with and entering, , abundant and , and a with strong . The published sources draw the distinction within his own work explicitly: of the signed they observe that, "unlike the style of the Shohei 25 dated piece" (正平廿五年紀の作とは異なり), it shows a wider temper combining into a broader , a richly varied workmanship. The smith thus worked in more than one manner, and the signed examples, precisely because they depart from the standard, are prized for the study of his range.
What sets him apart is therefore named by the judges themselves rather than borrowed from a neighbor. He is read against the school by lineage and against the wider Yamato tradition by province: his bright, dark, -inclined , his tight low , and the Kyushu cast of his steel are the features the published sources name as his own, and the dated is the document that holds them together. Within the Kongobyoe and Reizei line his is the name the school's shortened, unsigned most often carry, judged to him from that one dated standard, from the era, and from the manner of the group, the commentary cautioning on some blades that there is no decisive proof the hand must be his while still affirming the appraisal from the Yamato-toned and the narrow edge.
For the collector he is a thinly recorded but genuine name, valued for documentary weight as much as for display. He has no National Treasures and no Important Cultural Properties; his record runs instead through one and a score of blades, with the Shohei 25 dated and a recognized in the prewar Bijutsuhin. Provenance is sparsely recorded, held in private hands rather than institutions, the dated once in the Koizumi collection and the early Sadamori with Morotomi Yoshio of Fukuoka. Most of his blades are the of the tier, and these come to light only from time to time; a signed Reizei Sadamori is rarer still, and one of the published sources calls the signed a precious work "by which the range of the seldom-signed Reizei Sadamori may be apprehended." A privately held example, signed or , is a document of how a Yamato hand worked in , and a thing a collector encounters seldom.