@es_kan
Speculation on Lawyer Jin not knowing about the last weight. Contains spoilers.
Later in the webtoon, it is explained that the lawyers and the military forces in hell are people who died when they were still children. When they become adults, they are given the option to work in hell or to be reborn. If I remember correctly, the children do not go through the trials. It's probably the reason why Lawyer Jin didn't know about the last weight.