The reason why Davis still hadn't checked Fallen Heaven's power to kill Eighth Stage Experts is that those he met were all part of an Emperor Grade Power where numerous other Eighth Stage Experts or Ninth Stage Powerhouses exist. They held the helm of their families and saw to it that their juniors and uprising geniuses didn't die halfway.
If they managed to find that he was the one who killed their expert, then he would undoubtedly be chased to the end of the world to be executed. He didn't want to attract higher-level Eighth Stage Experts or Ninth Stage Powerhouses for a silly reason such as experimenting.
For this reason, he felt that he had to target lone Eighth Stage Experts to test Fallen Heaven's powers so that there won't be any repercussions in the future.
