Saturn (= Chronos, Time) is effectively telling the time by cutting it to pieces with his scythe, and the Babylonian spring sun god Marduk divided the night Tiamat (the ocean god in form of a great water monster) in half by a slash:

"... Marduk, die Frühsonne des Tages und des Jahres, wurde eben wegen dieses seines Charakters der Lichtbringer am Weltmorgen. Marduk, der die leblose, chaotische Nacht, die keine Gestaltungen erkennen lässt, besiegt, der den Winter mit seinem Wasserfluten, den Feind des Naturlebens, überwindet, wurde der Schöpfer des Lebens und der Bewegung, der Ordner des Regellosen, der Gestalter des Unförmlichen am Weltmorgen ...

Die Sonne, die des Morgens das Weltmeer durchschreitet und besiegt und das Licht bringt, lässt aus dem Chaos der Nacht zuerst den Himmel, dann erst die Erde hervortreten, spaltet das gestaltlose Reich der Nacht in die zwei Hälften, den Himmel und die Erde ..." (Jensen)

The Apophis snake is similarly ‘finished’ by ‘knives’:

Wilkinson comments that magic knives were involved in destroying the enemies of the sun at each dawn and the two sycomore trees between which the sun rises each morning were called the 'two knives'.

In South America the rainbow is compared to a kind of snake, responsible for lifting the sky up from earth to let light in (not an altogether beneficient action):

"... The Katawihi distinguish two rainbows: Mawali in the west, and Tini in the east. Tini and Mawali were twin brothers who brought about the flood that inundated the whole world and killed all living people, except two young girls whom they saved to be their companions. It is not advisable to look either of them straight in the eye: to look at Mawali is to become flabby, lazy, and unlucky at hunting and fishing; to look at Tini makes a man so clumsy that he cannot go any distance without stumbling and lacerating his feet against all obstacles in his path, or pick up a sharp instrument without cutting himself ...

... The Mura also believed that there were two rainbows, an 'upper' and a 'lower' ... Similarly, the Tucuna differentiated between the eastern and the western rainbows and believed them both to be subaquatic demons, the masters of fish and potter's clay respectively ...

... In South America the rainbow has a double meaning. On the one hand, as elsewhere, it announces the end of rain; on the other hand, it is considered to be responsible for diseases and various natural disasters [dis-aster]. In its first capacity the rainbow effects a disjunction between the sky and the earth which previously were joined through the medium of rain. In the second capacity it replaces the normal beneficient conjunction by an abnormal, maleficient one - the one it brings about itself between sky and earth by taking the place of water ..." (The Raw and the Cooked)

The serpent (rainbow) is responsible for the dis-junction. The paradisical normal state of watery darkness uniting sky and earth is disrupted by light, letting in all sorts of 'maleficient' creatures.

We can now better understand the role of Rigi, the great worm who lifts up the sky roof during the 2nd quarter, then dies and becomes the salty sea: