She confessed her astonishment at her light sentence when her father visited her at the jail.

她父亲去牢里探望她的时候，她承认自己对于受到从轻判决感到吃惊。

《柯林斯英汉双解大词典》

He was convicted of assaulting a police officer but he got off with a light sentence.

他被定了个殴打警察罪，然而却得到从轻判处。

《牛津词典》

The compassionate judge gave the young offender a light sentence.

慈悲的法官从轻判处了那个年轻的罪犯。

youdao

The trial of Iraqi journalist Muntader al-Zaidi, who shot to fame after flinging his shoes at former President George Bush during a press conference last December in Baghdad, ended with a relatively light three-year sentence.

VOA: standard.2009.03.12

Accordingly, 28 years was a "relatively" light sentence, even if it is -- practically speaking -- a life sentence anyway.

CNN: Peanut sentence sends a message

In it, the defense lays out why the defendant should get a light sentence (family, health, all around good guy), while the prosecutors want the maximum sentence (more years in prison).

FORBES: Doug Whitman Gets No Break on Prison Sentence, But Few Do

This is a light sentence given the dollars involved.

FORBES: Lauryn Hill Jail Time---What's A Fair Tax Sentence?