I’m trying to stay levelheaded about King Richard. What I meant was that there seems to be extraneous details here—about the order things were done in, first inscribe (“key is here”, on an empty(?) box), then put dagger in, or that it was written, not spoken. Many comments only enforce the importance of that.
The “real” answer seems to be one that effectively makes all kinds of communication useless, and what I’ve spent so much time on was trying to pin down the borders of this insanity, some marker saying “abstract logic application to real life* not allowed past this point”.
*) the use of physical boxes binding the riddle to “real life”