*valknútr?

The question was raised about the origins of this word, about whether
it was an ON word or a new creation. Apparently, it is used about an
interlocking, triangular symbol found on certain old heathen memorial
stones. The symbol consists of 3 interlocking triangles drawn as one
continuous line. Anyway, I can't find anything on this word. I doubt
that this word is ON. Does anyone know where the word comes from, or
who first used it? Lastly, does anyone know what the ON word was for
this ristubragð?

The symbol occurs, amongst other places, on a beautiful Gotlandic
stone carving that also features Óðinn riding Sleipnir, his horse.
Valkyriur also appear in the picture, it would seem. So my guess is
that the symbol's association with Óðinn is correct. But what was it
actually called in ON?

-K