Gentlemen -
The genesis of this story comes from the original name of this style of tsuba; Mukade. The Takeda army employed a troop of swift running messengers that carried orders from the command tent to the captains in the field; The Mukade-tai. They were conspicuous for their centipede hata-jirushi.
When promoted to membership in this troop, the story goes, you were directly or indirectly given the privilege of wearing this style of tsuba, a mark of said membership, by the lord, Shingen himself. Why the tsuba? Because you did not wear the hata-jirushi every day, but you always had your sword!
Reference Nihonto Daihyakka Jiten by Fukunaga Suiken I am pretty sure I wrote this up in To-Ron several years ago. Like any style it was oft copied and the "Shingen" appellation clearly excites us pedestrians more than "centipede tsuba", so it was natural for dealers to exploit it. The story clearly being lost over time...
-t