Please help me identify and understand the proper way to sharpen this odd edge

[JonathanCharles]

Hey BF friends!

I got this draw knife from the flea market a few months ago and now I need to use it. Upon inspection the edge seems to curve downward like a claw. Is it supposed to be that way? Is it a standard draw knife? How the heck do I sharpen it? Please educate me! I apologize for the poor photos--I'm a poor kid borrowing someone's cheap camera.

http://imgur.com/a/PQfGP

Thanks!

Jonny

 

[Jason B.]

I've always sharpened them on a stone.