AB Swords are constructed using AB (Anti-Barrier) materials designed by the Mother Knight that ignores the defensive super barriers that High Rank Beasts use, which render ordinary weapons useless.
Note that it is not the construction of the sword itself, but the AB material, which generates AB particles, (Ep0 - Ch2, Ep0 - Ch22) that allow the swords to dissipate shields. This has lead to a focus on higher AB particle generation rather than the durability of the sword itself, much to the disappointment of Pray. However, it is suggested that AB swords are still extraordinarily tough, compared to normal weapons. In AE-2, Number 30. Arondight was tough enough to withstand a blow from Ray that shattered the orbital elevator with no damage whatsoever.
Sword Ownership Edit
AB Swords are numbered according to the order they were made. They're given to a Knight when they officially become a Knight. A trainee uses alternative versions, with no numberings. However, some of these trainee swords are stated to be just as powerful as the numbered AB Swords. Sometimes, they are even tougher than the numbered AB Swords, due to other materials being mixed in place of AB materials (A trainee's sword contains less AB material than the numbered swords). This has led to several full Knights using their trainee swords over their numbered swords (Pray used her trainee sword in her battle against Anne, and only switched to Number 5. V when it was destroyed).
It has been stated that AB Swords are returned to the Knights after the death of the owner, or if the owner retires. However, this is not always the case. There have been several instances where the owners of the AB Sword kept their sword even after retirement. Lieutenant General Tinie kept his after he defected from the Knights and joined the AE. It's also common for families to hand down their swords as inheritances. Sometimes, AB Swords are used as tombstones for the fallen knight.