Sage Zavir was left aghast by what he saw.
He saw that Eren had managed to neutralize Hansen within just a couple of seconds. Even he wouldn't have been able to do something like that.
He could tell that what Eren had used against Hansen couldn't have been an Ability. However, he was unsure of what it actually was.
He neither experienced something like that taking place in his long life as a Sage nor had read about it in the old records of Anfang available to him.
Only now did Zavir realize that there was a bigger world outside the known limits of Anfang. He felt as if Eren had exceeded him and all the other Sages not in terms of Ranking Status but something much more profound.
He wanted to prevent Hansen from making any foolish mistakes. However, he felt that this experiment was worth it to test Eren's powers.