The Tomahawk Mastery Challenge was not an original challenge in Red Dead Redemption. It was added later as part of the Legends and Killers DLC to both the base game and Red Dead Redemption: Undead Nightmare. Now, with an updated version of Red Dead Redemption being released on the PlayStation 4 and Nintendo Switch, players can experience the original game and all of its add-ons, including the tomahawk weapon and its associated challenge.
Source：https://www.cbr.com/rdr1-undead-nightmare-dlc-tomahawk-mastery-challenge-guide/
