Regarding my job-hunting, the thing that left an impression on me was how the interviewer looked down on me. I felt a kind of arrogance and authority from him/her that made it clear that she/he was the one to decide whether I be hired or not.
ご質問ありがとうございます。
"Regarding my job-hunting"=「私の就活に関して」
"the thing that left an impression on me was"=「印象に残っているのは」
"how the interviewer looked down on me."=「面接官が私を見下しているようだったことです。」
"I felt a kind of arrogance and authority from him/her"=「その面接官から一種の傲慢さと権力を感じました」
"that made it clear that she/he was the one to decide whether I be hired or not."=「彼/彼女が私の採用を決める人間である、というのをはっきりさせるようかに。」
ご参考に!