In his book "All of Aikido", Yoshigasaki Sensei traces Misogi, as we practice it in Aikido, back to a samurai. This samurai was Yamaoka Tesshu (山岡鉄舟, 1836–1888). His disciple Ogura Tetsuju (小倉鐵樹先生, 1860-1944) founded the Ichikukai Dojo. There, Koichi Tohei practiced Misogi years before he started with Aikido, mainly with Hino Tesso (日野鐵叟, 1898-1987). The training was extremely hard. Tohei reported, that once, exhausted by a misogi, he discovered the principle of relaxation on the mats in the Aikido Hombu Dojo.
In his book, Yoshigasaki Sensei describes Misogi with bell and with bokken. In the following videos he explains another variant with kotachi, the short sword.