Ideas:

1. In this glyph the four internal markings are sorted into two groups. And these two groups are showing 'up' and 'down', like the Waxing and Waning Moon. Perhaps this means that there are two weeks during Waxing and two weeks during Waning Moon.

2. Compare with the preceding glyph! The space there covering the 'dark' event (between the visible 'up' and 'down' parts) is rather large. In the same way the space in the middle in the glyph above (between the wedge marks) is rather large. I guess these spaces, though not being of the same form (but anyhow in a way related to each other), reflect the same phenomenon.

3. Possibly it shows the chaotic dark part of the story covering Tuesday - Thursday. In contrast to the ordered worlds of Waxing and Waning Moon ('up' and 'down') there is no structure at all, a void.

Perhaps the week is structured in the same way as the month, i.e. there is a polarity with Sunday and Saturday as extremes with Wednesday as a point where there is battle. As e.g. in spring when Summer is grappling with Winter.