"If that truly is a being of pure good and not something else disguised, and I think it is being honest in its appearance, then we can probably trust it. I say probably because some beings of pure good are so self-sacrificing in their pursuit of the greater good that they are also willing to sacrifice others--they don't have the capacity to understand other people who aren't willing to sacrifice themselves to save others because they themselves are built out of pure altruism, so they automatically make the assumption that everyone is on board with that. This is, of course, not a perfect assumption to make with us mortals, as we have our own passions, dreams, and wishes, rather than being made out of cosmic good. Of course, that just means we need to think carefully about whether or not we are actually even capable of taking down Graven. To a being of pure good, it would be the correct decision for the Guardian to send us to try if it thought we had any chance, even if it thought our chance of success was slim and our chance of dying was likely."