I printed Brents article on making this hammer with Atlantic 33 ...he says after you finsh forging to anneal it in vermiculite or ashes then grind to the final profile.
he says Atlsntic 33 is a water quench alloy that requires no tempering.
he goes on to say in a coal fire use a pr of flat jawed tongs to turn the hammer from pein to face until both ends have been heated to a bright red or low yellow color. the area surrounding the eye should show very little color, perferably none. when the pein and face have reached the desired temperature, quench the entire hammer in water. up and down and sweral around...I copied the article from his web site but when I went back it was not posted any longer... hope this helps