A signed tachi designated at the 48th Jūyō session carries a two-character mei, Shigetsugu, cut boldly on the ura of a shortened tang filed in ō-sujikai, and the published commentary reads it as classic Ko-Aoe: "this tachi clearly displays the characteristics of Ko-Aoe." Shigetsugu is a smith of the Ko-Aoe, the early phase of the Aoe school of Bicchū Province. The published sources identify him with the craftsman recorded in the reference works as a son of Toshitsugu and placed in the mid-Kamakura period around Bun'ei (1264-1275); they note plainly that "this Shigetsugu corresponds to the smith transmitted in the meikan as the son of Toshitsugu, mid-Kamakura, around Bun'ei." The school itself is traced to Yasutsugu of the Jōan years, and works that do not descend past the mid-Kamakura are set apart as Ko-Aoe; among its representative hands the published record names Moritsugu, Tametsugu, Tsugie, Tsunetsugu, Toshitsugu, Suketsugu and this Shigetsugu, most of them carrying the character tsugu as a shared element of their names.

His surviving work is tachi, slender and well-shaped, with a deep koshi-zori and pronounced funbari, several still keeping their original tang. The hand that distinguishes him is a quiet one. Over an itame mixed with mokume, at times a closely packed ko-itame standing a little, he forges a steel somewhat dark in tone that tends toward sumihada, carrying the speckled jihada-madara and patchy jifu that are the Aoe jigane, with fine ji-nie and, on his most fully described blade, a clear midare-utsuri standing in the ji. The temper over that jigane is calm and archaic, a suguha base shallowly notare into which a small ko-midare of ko-gunome and ko-chōji enters. Ashi and yō are well present, the nie thick and in places particularly strong, and kinsuji and sunagashi run frequently along the edge. The bōshi runs straight to a yakizume-like finish with fine hakikake. The published sources call the effect old in feeling and rich in nie, the activity gathered not in towering clove clusters but in the small reversed-clove line and its internal work.

The jigane is where his school shows most plainly. The somewhat dark steel, the sumihada and jifu, and the crepe-like chirimen texture set the Aoe jigane against the brighter, cleaner ko-itame of contemporary Bizen, and the published commentary draws the contrast directly, judging Ko-Aoe work "on the whole somewhat subdued and quietly astringent in flavour compared with Bizen blades of the same period." Over that jigane the hamon stays comparatively restrained. The published sources praise the most fully described of his blades for being "archaic in the temper, well covered in nie," with ashi, yō, kinsuji and sunagashi showing within, a deeply nuanced and engaging manner rather than a flamboyant one.

Not all of his record is so quiet. One of his shortened, two-character-signed tachi opens instead into a dense, double-flower jūka-chōji-midare in nioi-deki with a tendency toward ko-nie, the ji an itame standing a little with sumihada and an utsuri-like reflection. The published sources note that, set beside his quieter suguha-toned work, the manner of the signature and the workmanship differ across his extant pieces, so the activity can open here into a richer clove-flower line. That blade carries a cut-in inscription recording its shortening in Tenbun 10 (1541) by Fukui Ukyō-no-suke Koremune Tadanō, a documented later history laid over an early hand.

What the judges single out separates him within his own school as much as from his neighbours. Compared with the brighter, cleaner steel of Ko-Bizen, his somewhat dark jihada with its sumihada and jifu reads as the Aoe jigane; and against the school's own conventions the published record notes a telling exception. The three prewar Important Art Object tachi are signed on the omote, which the commentary remarks is "although Ko-Aoe works, exceptionally bearing tachi-style signatures," whereas the Jūyō tachi places its signature on the ura in the usual Ko-Aoe manner, the tang filed in ō-sujikai; the placement of the signature and the file marks are exactly the points the published sources name as distinguishing the school from Ko-Bizen, and they cite them in support of the attribution. He stands among the named early hands of Aoe, the quiet Bicchū counterweight to the brilliance of Kamakura Bizen.

For the collector he is a rare early name, graded Jō saku by Fujishiro. He has no National Treasures and no Important Cultural Properties; his record runs instead through three blades designated Important Art Objects before the war and one tachi designated Jūyō, four designated works in all, and the published commentary calls the surviving examples precious, holding that "extant works by Shigetsugu are rare, and this one is precious; moreover it has high value as reference material for the study of the smith." Their provenance runs through the great daimyō houses: the three-character Shigetsugu saku tachi was transmitted in the Kishū Tokugawa family before passing to Hon'ami Kōson, another descended through the Tokugawa house to Tokugawa Iesato, and a third was held by Miyazaki Tomijirō of Kanagawa. So few of his blades survive, and so seldom does a signed Ko-Aoe Shigetsugu come to light, that a privately held example is a notable thing for a collector to encounter, valued less as an ornament than as a document of how the Aoe school worked in its earliest age.