Sweet mother of all that is shiney and pointy, a blade of artifical sapphire! Hmm, I'm thinking you won't have to worry about sharpening it for a long time. On the other hand, I wonder how brittle it is. I wouldn't try prying anything open with it, but that's just a s.wa.g. (scientific wild-ass guess).

Can a person buy a belt sander with diamond-powder grit? That would probably sharpen it. I'd do a search on the properties of sapphires and see what you can learn.

Okay, curiosity got the better of me and I did some research:
Synthetic sapphire crystals can be grown in cylindrical crystal boules of large size, up to many inches in diameter. Pure sapphire boules can be sliced into wafers and polished to form transparent crystal slices. Such slices are used for high quality watch crystals, as the material's exceptional hardness makes the face resistant to scratching. Since sapphire ranks a 9 on the Mohs Scale, owners of such watches should still be careful to avoid exposure to diamond jewelry, and should avoid striking their watches against artificial stone and simulated stone surfaces. Such surfaces often contain materials including silicon carbide, which, like diamond, are harder than sapphire and thus capable of causing scratches.

So, a silicon carbide stone should do the trick...

-Blast