When I searched for "grippen word" in Google Books, I got no hits.

When I searched for "grip and word" I got over 600 hits, mostly having to do with Freemasonry.

I did not see any that had to do with horsemen, but I didn't look as diligently as one might.

Even if "grip and word" was only meant as a metaphor, it is a good metaphor for secret knowledge or practice, so I believe it is correct.

Someone should inform The Elphinstone Institute.