Aspects are basically details that are relevant to the story. If the Rapier is an important item, you can easily expand it and instead of having one aspect like "exquisitely balanced rapier", you can have the masterfully crafted rapier which has a couple of aspects like "exquisitely balanced" and maybe some more describing the superior quality attached to it. Anyone using it can spend fate points on the aspects, to increase their fighting skills.
If you like you could even give the rapier a stunt or two, making it even more important. The rapier is either part of a character now, or a "character" in it's own right. Anyone using the rapier to fight gets the benefit of the stunts attached to the rapier.
If you want to put it over the top, you could even create the rapier as a fully fledged character, with the person wielding it as an aspect. It all depends on what part of the story is important to you. It's known as the Fate fractal, and I'm a big fan of it.