I was studying death note's first ending 「アルミナ」, and I found this phrase: 「流れる時間の中瞬く刹那的煌めきを」the dictionary that I was using (nihongo dera) said that both 「瞬く」 and 「煌めき」mean "to twinkle", but what's the difference between those two words?
煌めき is the masu-stem of the verb 煌めく. This 煌めき is used as a noun ("twinkling thing"). See masu-stem used as a noun. To be more specific, in this context, 煌めき seems to refer to twinkling/shiny moments in one's life.
As verbs, 瞬く and 煌めく are similar, but the former is focused on the quick brightness change, while the latter also describes something is bright/shiny.