Hmmmm.... Personally I see two ways of doing this:
1. Define the sword shape as two separate objects (i.e. the upper and lower side of the blade). Then add gradient layer effects to both objects, making sure that the gradients lead away from each other.
2. Create a metal effect using layer effects that is not smoothed any way. This will lead to a sharp edge that could resemble a blade edge.... with a lot of fiddling. You'll get artifacts around the sloping edge, though, that will probably need manual alteration later. To understand what i'm talking about just look at the sharp edges in the small letters in RoboUK's metal embossing tutorial
here.