Let me think,
if the blades are bent otherwise will say that the vane shall not unscrew and deliver the firing mecanism but well screw the arming rod in the fuze. Why ? That do me looking on UK Pist No 37 for squash the chemical glass.
I have not my Doc at home (where I am now!), look perhaps in this direction.
Other possibility, the thread of the arming rod is counterclockwise (we say lefthand). And I have also the same idea, the first amelioration of Pist No 37 when the pistol was unscrewed of his pocket fuze with a normal vane.
Yoda, the thread of the arming rod indeed is counterclockwise !