Various forms of magic exist, and they are used in different ways for different effects. One involves scribing runes onto an object to provide it with magical properties. This allows for enhancement of this o jets in ways that would not be normally possible. A sword that lights on fire for example, or a ring that places a protective barrier around the wearer when activated. This runes are infused with their own power when they were created, with a range of quality. Some are made to last for long periods of time while others fade away after a certain amount of use, in which case they would have to be reapplied or the object replaced completely. In essence, they are like batteries that last for a certain length, and lose power with use.
This extends to magic clothing, specifically made from the materials of animals. Dragon boots and handbags made from creatures can be outfitted with runes to enhance their effects. A handbag that can hold more than it should naturally, or can withstand certain conditions or hold particular powerful magic artifacts without disintegrating. Entire clothing lines have been built which focuses on this for of rune magic.
However, the skin of living things is not suitable for runes. Individuals wishing to power themselves up or give themselves other properties will be disappointed, because living skin is not a good conductor for magic. This sounds like a contradiction.
Why would this be the case?