彼の弱みに付け込むのはやめなさい。
Stop taking advantage of his weakness.

他人の弱みに付け込むな。
Don't take advantage of others' weakness.

ビルは不当にも弱みに付け込まれた。
Unfair advantage was taken of Bill's weakness.

ジョンはビルの弱みに付け込んだ。
John took advantage of Bill's weakness.

彼女の弱みに付け込んで。
Take advantage of her weakness.