Deal them a blow - Idioms by The Free Dictionary
deal (someone or something) a blow (redirected from deal them a blow)
deal (someone or something) a blow
To adversely effect or detract from someone or something. Getting a bad grade in my favorite subject really dealt my self-confidence a blow. Despite the company's recent success, the massive recall dealt it quite a blow.
deal somebody/something a ˈblow,
deal a blow to somebody/something be a shock for somebody; make something fail, etc: The death of her father dealt her a terrible blow. ♢ Losing his job dealt a blow to his hopes of buying his own house.