Suriage (Blade Shortening) Technology and Appraisal—Sword Modification from Tachi to Uchigatana, Value Assessment, and Identification Methods

What is Suriage?—Blade Modification Born from Changing Times

"Suriage (blade shortening)" is one type of modification that changes the form of a Japanese sword, specifically referring to the process of shortening the entire blade length by cutting and shortening the tang (nakago) of the blade. While suriage does not change the blade edge length (ha-naga), it was often performed with the objective of improving practical usability by shortening the tang portion, thereby changing the grip comfort and overall balance of the sword.

The etymology of the term "suriage" is generally understood to derive from the process of refining and polishing (polishing upward) the cut surface of the tang.

The historical background for widespread suriage lies in the fact that large tachi swords produced during the Kamakura to Nanboku-chō periods became impractical with changes in warfare tactics (from mounted cavalry combat to infantry warfare). Long tachi were unsuitable for the style of wearing as uchigatana at the waist, so it became common to reuse them as uchigatana by shortening the tang. From the late Muromachi period through the early Edo period, many masterworks of ancient blades were shortened and used as uchigatana.

Types of Suriage—Classification by Degree of Shortening

Suriage is classified according to degree as follows.

Minor Suriage (Kosuriage)

A state in which the amount of tang shortening is relatively minor, with a portion of the original tang remaining. In most cases, the original signature (the sword maker's name) is preserved, and some of the original nail holes remain. Part of the file marks (yasuri-me) on the tang are visible throughout.

Major Suriage (Ōsuriage)

A state in which the tang has been substantially shortened. The original signature (mei) is often partially effaced or completely lost. The original nail holes are also removed, with new ones drilled. The overall form of the tang has been altered.

Complete Suriage (Kanzen-suriage)

A state in which the original tang has been completely removed and the original signature is entirely lost. The entire tang has been newly formed after the suriage process. The original file marks do not remain, with new file marks typically applied.

Treatment of Signatures (Mei)—Folded-Back Signatures and Appraisals

How the original signature is handled during suriage is an extremely important matter in appraisal.

Folded-Back Signature (Orekeshi-mei)

When the original signature remains on a specific part of the tang, the practice of folding back the end portion of the shortened tang to preserve the part with the engraved signature is called a "folded-back signature." This allows the original signature to be preserved hidden within the interior of the shortened tang. The presence of a folded-back signature is an important positive factor in valuing a shortened blade.

Whether a folded-back signature exists can be confirmed by carefully examining the area around the nail hole and the lateral and end surfaces of the tang when observing the tang with the handle removed.

Supplementary Signature (Soemi) and Daimyo Signature

After suriage, the daimyo or sword merchants who commissioned the shortening sometimes add their own names as signatures on the tang. This is called a "supplementary signature" or "daimyo suriage." In famous blades reputed to have been shortened by renowned warlords such as Toyotomi Hideyoshi, Tokugawa Ieyasu, and Date Masamune, such supplementary signatures sometimes remain.

Appraisal Signature (Kiwame) and Later Signature (Nochi-mei)

The practice of later sword appraisers (such as the Honami family) placing a signature on a shortened blade that has lost its original signature as a result of their appraisal is called "kiwame (appraisal signature)" or "entering a later signature (nochi-mei)." Shortened blades bearing appraisal signatures of renowned appraisers such as Honami Kōon and Mitsutada possess historical value in themselves.

Characteristics of the Tang After Suriage—Identification in Appraisal

The fact of suriage can be confirmed through observation of the tang. The characteristic features visible in a shortened tang are as follows.

Shape of the Tang Tip (Cut Surface): The tang tip cut by suriage often has a different shape from the original tang tip. The tang tip of the original tachi often takes the form of a "sword-shaped tang (kengata-nakago)" or "slender tang (hoso-nakago)," but these characteristic shapes are lost after suriage.

Multiple Nail Holes: In shortened blades, the original nail hole and a newly drilled nail hole made after suriage may coexist. When the old nail hole remains near the tang tip and the new nail hole is positioned near the junction with the handle, this serves as evidence that suriage has been performed.

Discontinuity in File Marks (Yasuri-me): When the pattern of file marks applied to the original tang changes midway or is unnaturally interrupted, this indicates that the original tang was cut by suriage and new file marks were applied to the remaining portion.

Changes in Tang Thickness and Cross-Section: While the original tachi tang is often relatively thin and flat, when reshaped as a tang for an uchigatana after suriage, the cross-sectional shape may change.

Impact of Suriage on Value

Suriage has a complex impact on the value assessment of Japanese swords.

Negative Factors: Loss of the original signature, loss of the original tang shape, changes from the original state of manufacture, increased polishing history. Particularly when the original signature is lost through complete suriage, even if an appraisal signature is present, the evidential power as proof of the original blade is weakened.

Positive Factors or Neutral Aspects: Blades that have been shortened by historically prominent figures (Toyotomi suriage, Tokugawa suriage, etc.) gain added value from their historical provenance. When a folded-back signature is preserved, this contributes to the preservation of value. If the blade (blade edge length) and workmanship are in good condition, they are evaluated separately from the condition of the tang.

Distinguishing from Fraudulent Later Suriage

Points of focus in appraisal for distinguishing between legitimate suriage from the Muromachi to early Edo periods and fraudulent modifications made in later periods (false suriage):

Consistency of Age Patina (Rust Color): In legitimate suriage, the patina from decades of age after the suriage period is distributed uniformly across the entire tang. In fraudulent suriage (modern modifications), the color or quality of the rust differs unnaturally from other parts of the blade and tang.

File Mark Technique and Tool Marks: The tool marks and processing precision differ between pre-Edo period file marks and modern file marks. File marks that appear unnaturally fresh are a cause for concern.

Typological Consistency of Tang Shape: Verification of whether the tang shape after suriage is consistent with "the tang shape of the period and school in which the blade was made." Inconsistency suggests suspicion of later modification.

Suriage is a modification culture that necessarily arose in the history of Japanese swords and itself serves as evidence of the demands of the era and the skill of the blade smiths. For the appraiser, observing a shortened blade is also a task of reading multiple historical layers at once, from the era of its creation through the era of modification and down to the present day.