Sentence:  "That" the young Mr. Churchills liked—but they did not like him coming round of an evening and drinking <WSD>weak</WSD> whisky-and-water while he held forth on railway debentures and corporation loans. Mr. Barrett, however, by fawning and flattery, seemed to be able to make not only Mrs. Churchill but everyone else do what he desired. 
Meaning of the word marked with <WSD> tags:  Dilute, lacking in taste or potency.