In keeping with the theme of relatively easy to understand associations, Libra II brings together The World (Saturn) and Justice (Libra) resulting in the III of Swords. Saturn not only rules the second decan of Libra but is also generally exalted anywhere in Libra. I don't usually go for the whole Crowley "Lord of Blah" tarot card titles, but there is something kinda poetic in the description "Lord of Sorrow".
When I first started reading tarot I found the III of Swords really hard to interpret. I knew from all the LWBs that came with the first decks I owned that the general themes were loss and sorrow, but the symbolism of a heart pierced with three swords didn't make a lot sense to me. Surely there's better imagery to depict the feeling of loss and sorrow? The problem was that I was too young to have experienced the kind of sorrow that the sword pierced heart describes. It wouldn't be until my late teens and breaking up with my first real love that the visceral sensation of sorrow described in the III of Swords made sense. Now I get it.
I know there are a lot of different interpretations of this card depending on who you read. One common theme is something like a contract or promise. As I've said before in these decan posts, I think there's a strong desire to positive-wash the more difficult tarot cards. Real heart-piercing loss is a part of the human experience. This is why layouts in tarot are so critically important and having a well-formed question for context. If the III of Swords comes up in a reading it may be past sorrow, it may be someone else's sorrow, it may be the sorrow that comes from making a tough decision.
But it is always heart-stabbing ugly crying sorrow. Not everything is light and flowers and butterflies kids.
The Animal Totem tarot really gets this card. This may be my all time favorite depiction. The kind of sorrow represented by the III of Swords may fade over time, but it is never forgotten.