These cards are attributed to Chesed. The connection between the number Four and the number Three is extremely complex. The important characteristic is that Four is "below the Abyss"; therefore, in practice, it means solidification, materialization. Things have become manifest. The essential point is that it expresses the Rule of Law.
In the Wand suit, the card is called Completion. The manifestation promised by Binah has now taken place. This number must be very solid, because it is the actual dominating influence on all the following cards. Chesed, Jupiter-Ammon, the Father, the first below the Abyss, is the highest idea which can be understood in an intellectual way, and that is why the Sephira is attributed to Jupiter, who is the Demiurge.
The Four of Cups is called Luxury.
The masculine nature of fire permits the Four of Wands to appear as a very positive and clear-cut conception. The weakness in the element of water threatens its purity; it is not quite strong enough to control itself properly; so the Lord of Pleasure is a little unstable. Purity has somehow been lost in the process of satisfaction.
The Four of Swords is called Truce. This seems rather on the lines of "the strong man armed, keeping his house in peace". The masculine nature of air makes it dominant. The card is almost a picture of the formation of the military clan system of society.
As to the Disks, the heaviness of the symbol rather outweighs any considerations of its weakness. The card is called Power. It is the power which dominates and stabilizes everything, but manages its affairs more by negotiation, by pacific methods, than by any assertion of itself. It is Law, the Constitution, with no aggressive element.