In the Fellowship of the Ring, after Arwen outruns the Nazguls, she notices that Frodo is in a very bad state and seems to be very near death.
At this point she says;
"What Grace has given me, let it pass to him"
Which was followed by trippy-smithy and I usually didn't pay attention to it.
What did she mean by that?
Was it just a prayer? Or was she giving him some of her own life force to save him?
@John_Rennie pointed out that this scene is not there in the books. Considering this, the answer doesn't have to be perfect. It can be taken from examples of other such events from the Tolkien-verse or something from the real-world, where this scene was given an explanation.