に弱い

to be susceptible to; to be vulnerable to, to be bad at or have trouble dealing with something

→ に
phrase Uncommon #16,710
to be susceptible to; to be vulnerable to Used for having little resistance to something, such as alcohol, heat, attacks, or criticism.
JA: トムはお酒に弱いのよ。
EN: Tom can’t hold his liquor.

私は暑さに弱い。

I don't handle heat well.

スミス氏はこの種の批判に弱い。

Mr. Smith is vulnerable to this kind of criticism.

トムはお酒に弱いのよ。

Tom can't hold his liquor.

劉備は攻撃に弱い

Liu Bei is vulnerable to attacks.

— レッドクリフ Part I (2008)

あいつは内側からの攻撃に弱い分かりますか?

He's vulnerable to attacks from within. Do you understand?

— Godzilla Minus One (2023)

彼が投手として能力があることは否定できないが、かなりけがに弱い。

There’s no denying that he has talent as a pitcher, but he’s quite injury-prone.

phrase Rare #41,329
to be bad at or have trouble dealing with something Used after the thing someone struggles with, such as numbers, geography, or mornings.
JA: ちょっと数字に弱いのです。
EN: I'm not very good with numbers.

私は歴史に弱い。

I'm not good at history.

私はこの辺の地理に弱い。

I'm not very familiar with the geography around here.

ちょっと数字に弱いのです。

I'm not very good with numbers.

朝に弱いんです。

I'm not a morning person.