knock seven bells这个用法在英国比较流行,偶尔会在报纸上看到.这跟航海传统有关系,是 a nautical expression.A warrior association is appropriate for this idiom,since the origin is fighting ships and the ringing of bells to mark the passage of time on board.
Seven bells代表只剩半个小时了,差不多要把对方"结束"了,所以才有"狠狠修理对方"的意思.
This is the usual explanation of its origin:
A total of eight bells are struck to end a watch; to knock seven bells out of someone implies pretty severe handling — without actually finishing him off.
(Jackspeak,A Guide to British Naval Slang & Usage,by Rick Jolly,revised second edition 2007.)
The OED:"In Naut.slang phrs.to knock seven bells out of (someone):to beat (someone) severely; similarly,to scare seven bells out of:to terrify."