Dragon Lance of Depravity is one of the magical items described in Monster Girl Encyclopedia World Guide - Side II.
Guide Book Entry
In recent years, the Mamono Realm of Lescatie and the Dragon Empire of Dragonia have become allies, and many agreements have been signed between the two countries. They cooperate in a wide range of areas, such as trade, which facilitates the export and import of special products and goods, and tourism, which encourages people and mamono to visit and leave these states together. There is also an active joint training of dark knights and dragon knights and their training abroad.
At the same time, a large number of weapons that have been exported from Dragonia to Lescatie have undergone unique transformations here. One example of such a transformation is the Dragon Lance of Depravity. Also, it is the official equipment of the Order of the Dragon Knights and is the most popular among its knights ("Dragon Spear of Vow" p. 55 Dragonia). However, in Lescatie, under the influence of Druella's mana, it became a magical spear with more radical properties.
Originally, a "rage rune" was carved into the hilt of the spear, which explosively increased its wearer's energy and allowed him to exchange mana with the dragon at any time, even while sitting on her back. However, after transforming into the Dragon Lance of Depravity, like the change in meaning of the Blade of Salvation, the properties of this rune were also completely reversed. It is now "Rune of Rage Attraction": instead of increasing the energy of the spear owner, the rune transmits extremely strong excitement to the enemy and increases his energy.
In other words, the enemy who confronted the dark knight with this spear will, because of the effects of the rune, explosively gain energy, passion and fierce desire similar to that of a dragon. In such a state, which will by no means soon pass, he will be able to think of the dark knight with this spear in front of him only as his female. The spear is not only used by the dark knights, this weapon is drooled over by many mamonos who are not used to being honest with their chosen ones. Quite a few monsters seem to visit Lescatie to join the dark knights and obtain this spear.
Originally brought from Dragonia, this weapon proved attractive to dragons who cannot be frank with men because of their high position. As a result, the Dragon Lance of Depravity was imported into Dragonia. There are many stories of dragons who, nourished by the desire "I want a man to pounce on me," attacked men with this spear in order to convey their own desire for copulation with this weapon. And as a result, these dragons were raped by human men and became mere lecherous lizards that greedily take pleasure in it.
Dragons of Dragonia are not used to being obedient... this dragon lance of depravity may have been so named because they have fallen to the level of a common lizard.[1]