Pierce of Lescatie is one of the magical items described in Monster Girl Encyclopedia World Guide - Side II.
Guide Book Entry
During my time in the Mamono Realm Lescatie, I had the opportunity to see many mamono realm weapons made from mamono realm ore. However, it seems that mamono realm silver's ability to "easily absorb monster mana" seems to be able to provide a wider range of effects than I can imagine. This applies to things that cannot be seen in human lands - weapons that are created from mana accumulated in mamono realm ore that has been turned into various magical accessories with unconventional properties. One such item is the Pierce of Lescatie. At first glance it is an ordinary earring, but if you remove it from your ear and channel magical power into it, it will quickly turn into a mamono realm silver dagger. If you imbue your earring with magical power, that magic, once absorbed by it, albeit temporarily, will create a mana sword... The principle of this weapon is extremely simple: it makes full use of mamono realm silver's property of easily absorbing magical energy. In addition, the blade created by such an earring, reliably accumulating mana during peacetime, becomes stronger and sharper. The power of such a dagger is much higher than that of an ordinary mamono realm sword: an opponent pierced by it will lose all his powers in the blink of an eye. On the other hand, this magical blade is maintained through the consumption of magical power and will not last long after manifesting. As a result, after a while the earring will return to its original form. Mostly, I'm told, this accessory is used as a weapon for self-defense, and the dark knights use weapons made of mamono realm ore, such as the Lescatie Mamono Realm Swords mentioned earlier. However, for members of the order of dark knights who do not carry weapons such as mamono realm ore swords or spears, such as the dark strategists, these earrings seem to be a useful concealed blade "in case of emergencies". And I often see them worn in their ears.
However, the main reason the dark knights love these "Pierces of Lescatie" is that they can always wear earrings charged with their beloved hubby's mana. Therefore, even when they are away from their husband, they can feel his presence nearby, and, using the property of turning magical power into weapons, feel that they are fighting with him.
In addition, for unmarried dark knights, there is a special significance to the event when they hand a man such an earring that has been infused with their mana. This corresponds to a declaration of love or a "dedication of one's sword" to that man, also it is done with the purpose of keeping their chosen one from other mamono through their own magic. There is also a very passionate story that if a man wears such an earring given to him by a monster woman, in which the dark knight has accumulated her power, his body and heart will inevitably be captured by the possessor of this magic power.
By the way, has any mana accumulated in my own earrings? This weapon is just for self-defense, and it's perfect for sending to teacher who is still on a dangerous journey! ...Just for self-defense, yes, just for self-defense...[1]