In the Shodokan Aikido goshin-no-kata, there is a technique (the 24th one) where uke's steps with the tanto in both hands and draws it. Tori grabs uke's left hand and executes a tenkai-kote-hineri. Here is video of Abe-san and Sakai-san demonstrating it, as part of the whole kata.
The tanto is suppose to be one where the scabbard and handle look the same -- see above image. By holding onto it with one hand at one edge, the target cannot clearly see if the handle is in one's right or left hand thus giving the attacker an edge when drawing and either stabbing or slashing. Apparently, this knife type and attack are common practice with the Yakuza.
Is this weapon and attack common practice with the Yakuza? Was it ever? If so, is the attack practised correctly?
I want evidence of that either from personal experience (at either end) or verifiable records such as police, medical, or in written form from (non-fiction) yakuza literature. Anecdotes and speculations are of no interest whatsoever.
