Strung bow

It assembles itself the moment you are carrying all three pieces taken from the beasts, with no bench and no key, because anyone holding a bow, a rope and a purse already knows what to do with them. It is the only assembly in the game. The three pieces are not three prizes of the first chapter: they are the three verbs of the whole descent, to strike, to lower yourself and to pay, one per beast.

Right hand draws, left hand looses, and letting go of the right lowers the bow without spending the arrow. The string comes back in a little under a second, and the arrow leaves faster or slower according to how far you drew; under a quarter draw the shot does not leave at all. Then the arm tires, shakes more and more, and in the end gives way on its own: what you lose is the time, not the arrow. Arrows do not live in the bow, they come out of the bag one at a time, and with none the bow still draws and nothing leaves, so it is clear that the problem is arrows.

While the bow is in hand the lamp hangs at your hip. It keeps burning, but it lights from a hip instead of from where you are looking, and that is the declared price of a two handed weapon. It never enters the bag, so it costs no cells and cannot be lost: putting it away means slinging it across your back.