を軽んじた

took … lightly

→ を
phrase Rare #45,084
took … lightly The particle を marks the thing that was taken lightly. 軽んじた is the past form of 軽んじる.
JA: 彼は医者の忠告を軽んじた。
EN: He took the doctor's advice lightly.

彼らはその情報を軽んじた。

They underestimated the importance of that information.

彼は私の不平を軽んじた。

He made light of my complaint.

彼女の警告にも関わらず、彼はそのことを軽んじた。

Despite her warning, he made light of it.

彼は自分の病気を軽んじた。

He made light of his illness.