One of the names for Saturn in Polynesia is 'Dripping Water' (in Hawaii according to Makemson). At least some of the Polynesians regarded the planet to be a weather indicator. I think this glyph very well could be 'read' as showing dripping droplets.

There is a similar type of glyph sometimes found in the texts of rongorongo:

This seems to be some kind of plant.

But the Saturday glyph (see top) is not exactly the same. If we see 5 droplets in this glyph, then possibly in the center there is meant to be a canoe (like when in Tuesday we probably have a red canoe for Mars). If so, I guess this canoe is black, the colour of Saturn. Black as earth.

Earth is the element of Saturn.