noun
adding a crowning touch of beauty; making excellence even better
A yojijukugo meaning to add something beautiful or excellent to something already outstanding, like adding flowers to brocade. Often used in formal or literary contexts.
彼女の歌声にピアノ伴奏が加わり、まさに錦上添花の出来栄えだった。
With the piano accompaniment added to her singing, it was truly a case of adding a crowning touch of beauty.
画竜点睛 refers to adding the final, crucial touch that brings something to life, while 錦上添花 emphasizes adding extra beauty or excellence to something already splendid.
From Chinese 錦上添花 (jǐn shàng tiān huā), literally 'adding flowers to brocade', a metaphor for making something excellent even better.