One: (handsome) decline; Recession. Such as: old and weak.
Two: (Cui) 1. Decreasing according to certain standards. In ancient times, mourning clothes were made of coarse cloth and draped over the chest.
Judging from the poetic context, "decline" should be reduced, that is, the accent has not changed but the hair is loose and reduced.
Moreover, the ancients paid attention to rhyme, and "decline" should rhyme with the ending word "hui" in the first sentence.
Therefore, the word "decline" in the sentence is pronounced "Cui" with a sigh.