Durability of the weapons may depend on the user's will.
How long the blade lasts depends on the users skill and power, some may need near constant attention, others are effectively permanent.
Kratos (God of War series)
Link (The Legend of Zelda series)
Kurohime (Magic User Kurohime)
Ryu Hayabusa (Ninja Gaiden series)
Jack (Samurai Jack)
Hope's Dagger (Buffy the Vampire Slayer: Chaos Bleeds)
Blade of Olympus (God of War series)
Master Sword (The Legend of Zelda series)
Ultimate Sword (Magic User Kurohime)
Dragon Sword (Ninja Gaiden series)
Hope's Dagger (Buffy the Vampire Slayer: Chaos Bleeds) is a holy weapon forged from the very first ray of light ever to shine upon the Earth, and the only weapon capable of harming the First Evil.
Jack (Samurai Jack) possesses a magic sword that forged by the deities Odin, Ra, and Vishnu, and powered by the righteousness and Qi of his father. The sword is capable of cutting through any mundane substance as well as destroy any evil it comes in contact with.
Kurohime (Magic User Kurohime) wielding the Ultimate Sword, which contains the four Spirit Kings, and possesses so much power that it can cut through anything, even the Six High Gods and an entire planet.
In many incarnations, Link (Legend of Zelda) often wields the Master Sword. Blessed by the Goddess, Hylia, the blade possesses the abilities to repel evil, protect its user from corruption, absorbing energy in various forms, and possesses a mystical link that allows it to only be wielded by those who posses the soul of the goddess's chosen hero.
Ryu Hayabusa (Ninja Gaiden) possesses the Dragon Sword, a weapon carved from the fangs of one the Divine Dragon Deities and infused with its power. The sword can only be wielded by the strongest and most spiritually pure of mankind. Once combined with Eye of the Dragon, it becomes the True Dragon Sword, possessing unrivaled power that is capable of upsetting the balance of the world.