My granchild Clara, soon to become three years old, suggested that the right part of this glyph is showing a knife.

I think she is right in a way, because according to the Chaldean astrologers each of the seven 'planets' rules one day of the week. And a ruler must have a way to enforce, e.g. a knife.

Whether the instrument in question is a knife, a spear, a stick or a staff symbolizing power, is of secondary importance.

What is important is the idea that in the beginning of each row showing glyphs for a certain day there ought to be signs indicating the ruler of the day, the officer in charge.