Sadazane is recorded in the meikan as a son of Fukuoka Ichimonji Munetada, with his period of activity placed around the Hoji era (1247--1249) of the early Kamakura period. However, the NBTHK has consistently observed that extant tachi attributed to Sadazane display workmanship that appears, if anything, more archaic in tone than that of Munetada. This has led some authorities to regard him as a smith closer in character to the Ko-Bizen group rather than the mainstream Fukuoka Ichimonji line. Indeed, swordsmiths bearing the name Sadazane are found within both the Ko-Bizen lineage and the Ko-Ichimonji lineage, and their workmanship and signature styles closely resemble one another such that an immediate distinction is sometimes difficult. Nevertheless, the majority of his designated works are attributed to the Ichimonji school, and it is within the Ko-Ichimonji tradition that his artistic identity is most firmly situated.

Sadazane's characteristic style centers on ko-midare tempering with strong nie, a manner the NBTHK repeatedly describes as conveying an archaic flavor. His hamon is typically suguha-based, mixed with small choji, ko-midare, and ko-gunome, with abundant ashi and yo and frequent kinsuji and sunagashi. In his more flamboyant works, choji-midare mixed with gunome appears, and occasional tobiyaki and yubashiri-like nijuba are observed. The jigane is forged in itame-hada or ko-itame, with thick ji-nie and chikei; a distinguishing trait is that utsuri is not especially conspicuous in many of his works, setting him apart from other Ko-Ichimonji smiths among whom prominent jimadara-utsuri is common. When utsuri does appear, it takes the form of faint mottled or jimadara patterning. His tachi characteristically present elegant forms with high koshizori, pronounced funbari, and ko-kissaki, producing what the NBTHK terms a dignified tachi silhouette. The signature is consistently a boldly proportioned two-character mei cut with a fine chisel, placed toward the mune side -- a distinctive trait that strongly reflects the characteristics of his hand.

Sadazane occupies a position of particular scholarly interest within the Ko-Ichimonji group as a smith who inherited the style of Ko-Bizen while adding further novelty. The NBTHK has noted that the areas where ha-nie becomes thick in his work are expressive of a manner of workmanship that could only be produced by this smith. His finest blades are praised for jigane that is "truly of excellent quality," with bright nioiguchi and frequent internal activity that makes them "highly rewarding to appreciate." Signed works by Sadazane are described as few, and those retaining ubu nakago are singled out as especially valuable documentary material. Several examples are noted for their kenzen state of preservation, with the tightness of the nioiguchi cited as evidence that the blades have not undergone excessive repolishing. At least one work is compared to the National Treasure "Kitsunegasaki" Tameji for its exceptional vigor and soundness. Across the corpus, the NBTHK characterizes Sadazane as a smith whose subdued yet technically accomplished workmanship clearly displays the characteristic features of the Ko-Ichimonji lineage, and whose best works stand among the finest superior examples of that tradition.