J.A. Henckels 72 1/2 "Solingen Zwillingswerk" w/interesting curvature of the edge.

[rehargraves]

I recently purchased a J.A. Henckels 72 1/2 "Solingen Zwillingswerk."

As you can see from the picture, the edge has an interesting curvature to it. I'm new to straight razors so I don't know if this is a defect or if the blade was manufactured that way. I got the blade for less than $10 on Ebay so I figured it was worth it either way. Also, I consulted the dating chart for Henckel razors but I was still having some difficulty nailing down a manufacturing date. Anybody want to drop some knowledge on me? Thanks.