What is the explanation of Yang Guo's three swords in Jin Yong's novel {The Condor Heroes}?

1 Li Ling is strong and invincible, and it is weak to compete with Heshuo; 2 soft sword, Wei Zi, it is ominous to accidentally hurt the righteous, and it is abandoned by the deep valley; 3 Tie Xuan epee: epee has no front, and clever thinking is ineffective. Before the age of forty, make it run wild all over the world; After forty, you should stop obsessing about things. All plants, trees, bamboo and stones can be swords, and you are gradually entering the realm of no sword over a sword.