"Metaphors are safe. Sarcasm isn't. Most Others can't lie, especially older ones, but there are exceptions.
The reason for that boils down to the spirits. There's a collection of half-aware insubstantial beings that surrounds us. Talking about a single spirit, in this context, makes about as much sense as talking about a single bit of air. It's the aggregate that matters. They have short memories and are very literal with their interpretations. The Awakening ritual, when you become a practitioner, marks you as a person to listen to. If you tell a lot of lies, they have a lower opinion of you. You'll be less powerful, your enemies will be stronger, and you'll have bad luck. That's what karma is.
The same thing can work the other way. You've run across dangerous Others how many times before today? Most of them would have been bound by the Seal of Solomon, but not all. And even those that aren't rarely attack wantonly, because they know chance will side against them. To an extent, talking about the spirits and the universe can be interchangeable.
The other thing is that spirits are very old-fashioned. For instance, if you tell someone about our world, the spirits will see it as them being "one of yours." You'd be responsible both for any slips they might make and for what happens to them. That's why I asked how much you knew before healing you. If you had said something about the ogre and the naga being costumed people, I would have said your injury must not be as bad as you thought it was and healed it partially."