<P> The "Ultimate Champions Edition" (season 4) and "Rookies Edition" (season 5) each featured five smiths instead of four . The smiths were required to forge a particular type of blade at their homes and bring those weapons to the studio for a preliminary test . One smith was eliminated based on the results of this test, after which the competition proceeded through the normal three rounds . </P> <P> Wil Willis is a former Army Ranger and decorated Air Force para-rescue specialist . Willis' previous television experience includes Special Ops Mission and Triggers, two series that aired on the former Military Channel . </P> <P> J. Neilson, a knife and sword expert, holds the rank of Master Smith within the American Bladesmith Society . He has over 20 years' experience in making knives and edged weapons . He examines the weapons' technical qualities and tests their durability . In Season 3, Neilson took a leave of absence in order to have surgery on his hand; Jason Knight, another ABS Master Smith, filled his seat on the judges' panel during that time . Neilson appeared alongside Knight for the Season 4 premiere, then resumed his seat in the eighth episode . Starting with the 21st episode of the fourth season, he was replaced by two - time Forged in Fire champion Ben Abbott . </P> <P> David Baker, a Hollywood prop maker who has appeared on the Spike series Deadliest Warrior, is an authority on weapons history and an expert on replicating period - accurate weapons for both museums and films . He judges the weapons' historical accuracy and aesthetic beauty . </P>

How did ben become a judge on forged in fire
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