armor, helmet and shield
Rare historical term for the three main pieces of protective gear: armor, helmet, and shield. Not used in modern everyday language.
In old documents, 'equipping the three leathers' refers to the three items: armor, helmet, and shield.
three years of the sexagenary cycle associated with upheaval
In Onmyōdō (陰陽道), refers to the years 革令 (kakurei), 革運 (kakuun), and 革命 (kakumei), which are the 1st, 5th, and 58th years of the sexagenary cycle, traditionally considered times of civil unrest. Highly specialized term.
See also: 陰陽道
In Onmyōdō, it was believed that political upheaval would occur in the years of the three reforms.