The name, Tekki, refers to the distinctive feature of this kata (and the other two Tekki forms), its horse riding stance (kiba-dachi). The legs are set in a strong, straddling position as if on horseback, and tension is applied to the outside edges of the soles of the feet with the feeling of gathering the strength in toward the center.
Videos of Funakoshi Gichin kata at Keio University in 1934 (the producer dates the films 1924, but the same production contains footage of Kichinosuke Saigo, first president of JKA performing Empi and Yoshitaka Funakoshi (who didn’t come to Tokyo until 1932) performing Heian Godan).