What is Katte Sagari in Japanese Katana terminology?

The term "Katte Sagari" (勝手下り, かってくだり) refers to a specific pattern of file marks on a Japanese sword. In this pattern, the file marks are angled slightly downward from the blade edge towards the spine. This is in contrast to the "Katte Agari" (勝手上り) pattern, where the file marks are angled upward from the blade edge towards the spine. It is often said that the "Katte Sagari" pattern is commonly seen on swords made by left-handed swordsmiths. This terminology is used to describe the specific characteristics of the sword's structure, contributing to its overall aesthetic and functional design.