Sadakiyo belongs to the Hosho group of Yamato Province, one of the five classical Yamato traditions, which resided in Takaichi District and flourished from the late Kamakura period into the Nanbokucho period. According to the meikan (sword signature references), Sadakiyo is recorded as a son of Sadamune, and his working period is placed around the Genko era (1321–1324), though some sources alternatively record him as a son of Hosho Kunimitsu, and it is considered likely that there were smiths of the same name across generations. He stands among the accomplished makers of the lineage alongside Sadamune, Sadayoshi, Sadaoki, and Sadamitsu, all sharing the character "Sada" (貞) as a common element in their names — a hallmark tsuji of the Hosho group. The NBTHK consistently identifies the Hosho school as the tradition in which individuality of style is most conspicuously evident among the five Yamato schools.

Sadakiyo's forging is a thoroughly masame-hada — the all-over so-masame structure that is the defining technical signature of the Hosho lineage — densely worked, well refined, and compact. Thickly applied ji-nie and abundant chikei characterize the jitetsu, with nie-utsuri appearing in finer examples. The hamon is a suguha-based temper, frequently becoming markedly hotsure along the habuchi, displaying vigorous activity in uchi-noke, kuichigai-ba, nijuba, and even sanjuba, together with kinsuji and sunagashi. The nioi is deep, ko-nie adheres well, and the nioiguchi is consistently described as bright and clear (saeru). A recurring structural observation notes that the hardened width broadens from around the monouchi upward, with nie becoming one step stronger in that region. The boshi is vigorously finished with hakikake and terminates in yakitsume — another hallmark of the school. On the nakago, higaki-yasurime file marks and a bluntly cut-off tang tip are characteristic. Signed works bearing the "Fujiwara" honorific are only sparsely encountered overall, though in Sadakiyo's case they are seen with some frequency. His signature characters tend to be linear, with conspicuous reverse-chisel strokes, a mannerism shared among the smiths of this group. Extant works appear in two types: somewhat larger, robust examples of imposing build, and comparatively smaller pieces typical of Sadaoki's usual manner.

The NBTHK appraisals repeatedly affirm that Sadakiyo's work displays the characteristics of the Hosho school so fully that nothing is left to be desired, and that his finest pieces should be termed representative works not only of this smith but of the school as a whole. The various smiths of the Hosho group do not present sharply differentiated personal individuality, yet Sadakiyo's output is acclaimed for both workmanship and state of preservation. His signed pieces are described as exceedingly few and precious, with no dated examples yet observed, lending particular scholarly weight to each authenticated work. Within the broader Yamato tradition, the Hosho group's emphatic masame forging, nie-laden suguha, and vigorous boshi constitute a technical idiom of the highest individuality, and Sadakiyo stands as one of its most accomplished representatives.