+1 Mark, delete it. Make sure you have a backup of your manuscript for the day, you won't lose it. Then delete it and try something else.
Psychologically speaking, a major problem for writers is our own short-term memories and a heavily biased "moment" of how we perceive the real world and the world and characters we are writing. So when a phrase seems brilliant to us, it is often because we are relying on a state of mind or remembered circumstances that is NOT produced by the writing on the page.
It is kind of the "inside joke" phenomenon, without realizing you are telling an inside joke: The context of the brilliance was in your head, not on the page, and by the time you came back and read it: The context inside your head had dissipated, replaced by a series of others. So you read it as readers would have seen it.
It isn't like a joke. The first laugh at a joke means the punchline really did punch you. The next time you don't think the joke is complete garbage, you just aren't surprised a second time because you learned what is coming. With a joke we can still think it a clever twist, interpretation or reversal, there can even be another laugh in it, if it is good enough. But you laughed and that is all the evidence you need the joke delivered an unexpected but logical punchline.
A powerful phrase that no longer seems powerful, or seems trite, is different. Now what you thought was good seems bad, and the reason is the power was in the mental context of when you wrote it, and after a nights sleep that context is gone.
Truly powerful phrases grounded in the context provided by the writing leading up to them will still "read right" after a few days away from them, you will still be proud of them.
Be warned they can get stale if you read them again and again and again in a sitting. That is ALSO a mistake, you are memorizing the scene too much.
Write your scene. Go through it once, and fix any problems. Put it away until you have slept a night (work on something else) then read it and fix any problems. When you can read it through and like it all, consider it done (and do it all again in the future, of course, to make sure the whole story is properly connected).
And pay attention to your mind. Not everything in it is on the page, but everything in it can influence what you personally get out of the page. You have to take measures, through repeated "cold reads", that your mind is not helpfully filling in a bunch of gaps, and making poor writing feel good to you.