Corrected entry: Garth, shape-shifted as Spock, applies the Vulcan nerve pinch to Marta. Since Garth can only imitate the physical appearance of someone and not that person's life experience, Garth would have no knowledge of the Vulcan nerve pinch. The same could be said of when Garth shape shifts into Kirk - if Garth had Kirk's knowledge, he would have known the counter sign that Scotty used to challenge him for the beam up.
A Piece of the Action - S2-E17
Corrected entry: The book "Crime Boss of the Twenties" is in both Krako and Oxmyx office but it's not said that there are two books left behind.
Correction: It's discussed in the show how good the Iotians are at imitating things. That, combined with the fact that the book has become their guide on how to live, makes it highly likely they have recreated the book and distributed it throughout the planet.
Just what I thought - Krako may have had another copy.
Correction: May have been another copy.
Correction: It seems more likely Garth's henchman simply played along to convince Kirk Garth was Spock.
Correction: Garth, prior to being able to shape-shift and going insane, was a well respected Starfleet Captain and skilled tactician. In fact, he was required reading at the academy. Captain Garth would no doubt have extensive knowledge of Vulcans and the Vulcan nerve pinch, including learning how to do it.
Bishop73