[Ibrîniðilpathânezel]

Which goes to show that "mighty" probably had no clear distinction from "power" or "influence," as Tolkien generally used it. But since this use is coming out of the mouth of a character rather than in the narration, one might argue that this is Galadriel's interpretation (or misinterpretation, as may be) of the word, if one wanted to press the issue. Personally, I think Tolkien did not have the same distinct definition of "might" as he did for "power." Of the latter, he went so far as to say that "'power' is an ominous and sinister word in all these tales, except as applied to the gods" (letter 131), which to me implies that he gave a good deal of thought as to how he wanted to use the word. There is no such statement in reference to "mighty," which leaves it open to more liberal interpretation, I think.