There were 2 types characterized by the difference of their surfaces: one is "tagane-uchi (nicking with a cold chisel)" and another is "noshimeuchi (nicking during flattening process.)"
表面が「たがね打ち」のものと「のし目打ち」のものがある。 - Wikipedia日英京都関連文書対訳コーパス
Lastly, the craftsman carves his own name, address or year the sword was made on into the Nakago (core) as Mei (an inscription) with a Tagane (borer).
刀工は最後に鑿(たがね)を使い、自らの名前や居住地、制作年などを茎に銘を切る。 - Wikipedia日英京都関連文書対訳コーパス
It is a hachiryokyo (eight-lobed bronze mirror) and designated as a national treasure; the standing statue of Senju Kannon with kenzoku (one's family and relations) are carved with tagane (chisel) on the mirror side, and on the back side of the mirror, Hosoge-mon (flower motif) is carved in the center as well as butterflies and birds in four directions.
鏡面にタガネで千手観音の立像と侍立する眷属を彫り、背面には中央に宝相華文、四方に蝶や鳥を配した図柄の八稜鏡であり、国宝に指定されている。 - Wikipedia日英京都関連文書対訳コーパス