assassin's creed hidden blade

i had a cool idea for hidden blade
we need 3 springs (the third one is to keep the rope strained and to activate the second trigger  both springs have |dX |>0: dX1 > 0 ,dX2<0
(one spring for showing the blade, ione - for hiding , unstrained length the same)
then man pulls the rope connected with  the coil and this releases trigger A
it cause spring 1 to reduce its length
the blade appear
then man releases the coil and activates the second trigger (B), which cause the blade's hiding

it is only scheme, in real life it will take more springs and parts

Picture of assassin's creed hidden blade