The idiom "putting the finishing touch" is related to Zhang Sengyao, a painter from the Northern and Southern Dynasties. Legend has it that once he added eyes to the dragon he drew, the dragon would "fly away" This idiom often refers to a person who points out the essence at key points when writing an article or speaking, making the content vivid and powerful.
It is also often used to praise the exquisiteness of other people's creations.