Some more input ::grins::
Again, if what I've been researching and reading I'm understanding and intepreting correctly, in the above image, to the left, is the contact and arming mechanism. The central, 2-bladed prop is the arming mechanism; it had to spin so many revolutions (equivalent to the 300 meter arming distance) before the pistol/torpedo is armed. The four outer blade arms are for off-90 degrees contact detonation. Striking square on would transfer the contact impact through the central 2-bladed piece, while an off-square impact would push back one of the outer bladed arms and set off the fuze.