Kiyosada belonged to the Nio group of Suo Province, a lineage tracing its origin to Kiyotsuna. Among extant works by the school's progenitor, the earliest is a tachi dated Bun'ei 2 (1265), and the line continued through the Muromachi period and even into the shinto era. Smiths signing "Kiyo" (清) as a leading character are a hallmark of the school. According to the meikan, smiths named Kiyosada are recorded in eras such as Kakitsu, Daiei, and Tenbun, though a kodachi in the Imperial Collection is appraised as a Nanbokucho-period work -- described as the son of the second-generation Nio Kiyomitsu -- making it the earliest known example under this name.

While the style of Nio work conveys a strong Yamato-den temperament, the NBTHK notes that the flowing grain is "not as conspicuous as in Yamato blades" and the nie is "comparatively restrained." The kitae is typically tight ko-itame with a tendency toward masame, accompanied by ji-nie and slight chikei. The hamon centers on suguha -- from medium suguha with brightened nioiguchi in earlier works to suguha with gentle notare and active yo in later examples. Works at times show utsuri, and the tang tip in katakiri form is a distinctive feature. Later Tenbun-era pieces display kurikara carvings executed in ranma-sukashi style, demonstrating the characteristic manner of late Nio craftsmanship.

The NBTHK appraises Kiyosada's works as clearly demonstrating "the characteristic manner of contemporary Nio workmanship," and the Nanbokucho-period kodachi in the Imperial Collection is described as being "in healthy condition with excellent workmanship" -- a rare survival of which "very few similar examples survive today." Signed examples remain comparatively few across all periods, lending additional significance to each extant blade as reference material for the study of Suo Province sword-making.