Mars and Tiw share a day. They might also share a symbol: ♂︎ ᛏ. The earliest symbols for Mars the planet were of a pointed spear, or a spear with a shield drawn as a circle with a line running through it. We still use a shield and spear to mean Mars. He is a warrior like Tiw, both recognizable by their weapons, forever on a journey over the obscurity of night.