Sunnobi tanto (寸延び短刀) are larger than ordinary tanto, with nagasa (blade length) a sun or two above 1 shaku (sun nobi, “a sun longer”, from nobiru, to stretch or lengthen). Though there is some area of crossover with hira-zukuri ko-wakizashi and they may have sori similar to ko-wakizashi, the simplified difference would be that they are still designed with tanto geometry rather than wakizashi proportions and form.
An utsushi (写) is a careful and exacting replication of an existing work, undertaken for the purpose of study and further understanding of the process, techniques, and historical mindset of the original craftsman.
This project is an utsushi-type study of one of the kata (forms) made several years ago from the tracings of famous swords. The profile is closely based on the lovely form of an original named Shuhan, forged by Sadamune (相州貞宗), a Kamakura-era (~13th century) master swordsmith. Originally this was planned to be a rustic satoyama style blade but during the process some interesting details of the layered mining-car rail steel appeared and the decision was made to polish the blade more clearly to see the hada better.
A kata is a pattern or form used for study or for reference when creating an utsushi blade. The exercise of accurately making kata based on the work of historical smiths is an excellent way to train the eyes, mind, and body to create proper tanto forms. The most important aspect of making kata is to work carefully to be as true to the original lines as possible.
長さ/刃長 Nagasa: 11 sun 1 bu 5 rin (338mm)
元幅 Motohaba: 1 sun 1 bu (34mm)
重ね/元重 Motokasane: 2 bu 5 rin (7.5mm)
反り Sori: 1 bu 2 rin (3.5mm)
中心/茎 Nakago: 3 sun 2 bu 4 rin (98mm)
柄長 Tsuka: 4 sun 8 bu 5 rin (125mm)
拵全長 Koshirae: 20 sun 6 bu (525mm)
形 Katachi: hira-zukuri, iori-mune
刃文 Hamon: suguha, with ubuha
帽子/鋩子 Boshi: ko-maru
中心/茎 Nakago: futsu, kuri-jiri, as-forged, one mekugi-ana
銘 Mei: mumei (unsigned)
拵 Koshirae: chisagatana, issaku (with the addition of nine antique components)