This is Saturday:

Saturn moves slowly against the background of the stars because this planet is so far away. And a person who moves slowly must surely be very old. Young people are quick and full of life, whereas old people who move towards their death are in no hurry.

Is the last glyph (no. 8) showing the spirit arising towards heaven? Is this type of glyph to be translated as 'spirit in the sky'?

The 6th glyph is perhaps a rei miro, i.e. a wooden pendant shaped like a boat which only chiefs were allowed to wear. If so, then that would suit Saturday, because that is the day of the chief.

The 7th glyph looks quite like glyph no. 4 in Sunday and no. 9 in Thursday, but it could presumably not denote exactly the same thing. It could in principle mean anything, or perhaps it could refer to something abstract. But if I were forced to guess I would propose that it shows a 'spirit leaping-place' (reinga). On many Polynesian islands such a place was necessary for the spirit to be able to launch itself up into the sky.

The 2nd glyph I leave to the reader for the moment.