Here the word "forward" represents progress, and the word "hands" represents their control. AT: "made progress under their supervision" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This idiom refers to the lifespan of Jehoiada. AT: "for as long as Jehoiada lived" or "throughout the lifetime of Jehoiada" (See: [[rc://en/ta/man/translate/figs-idiom]])