Why did Allah Almighty repeat the words "haraj" (blame/hardship) and "buyutikum" (your houses) in verse 61 of Surat An-Nur, while He did not repeat the word "haraj" for the weak and the sick in another verse? And is there eloquence in that?

Repetition in the Holy Quran is a rhetorical device that suits the context. The context may necessitate brevity or elaboration. The repetition of the negation of hardship for the blind, the lame, and the sick in the verse (24:61) came due to the variety of reasons for hardship for each of them. As for the other verse, it was not repeated because they shared a single ruling. The repetition of the word "houses" came to dispel the illusion that everyone shared one house, for each has his own house.