A crescent blade is exactly that, a blade shaped like a crescent moon. It is made of a magical, metallic substance that fairies can make out of thin air. It is dangerously sharp on both sides and can act as a practical tool or a weapon. Peaceful fairies may use this to collect fruit from trees or as cutting tools for cooking.One quality of the blade is that it is like a boomerang, it comes back to the thrower but not in such a fashion that it could kill them, but that is only if it has not lodged itself into an object. Things that are hit with the blade may be carried back with it or on occasion, just send the item flying back to the thrower. You know, with magic! It doesn't quite matter how much effort goes into the throwing, since they pick up speed on their own and slow down on the return. It can be thrown in a way that it does not return however, as fairies can summon up a number of them and generally don't care what happens to these disposable blades. They degrade within a few minutes anyway, returning their magice either to the earth or to its summoner.
Azelea once attempted to behead Mye with one of these blades but ended up with Claire's noggin in her hands instead. Her summoning hand still buzzing with magic, as well as her distance, may have been a key factor in the creation of Lemrya.