That notch, that deep and in that location, reduces the durability of that knife by a large margin. Due to the proximity to the fuller, I would estimate probably by 50% or worse. The SDFK would have been a better choice for this treatment as would a shallower notch farther up the spine.
This will limit your margin for error when batoning, chopping, prying etc. In my opinion, this loss of functionality is a larger offset than having a dull area on your edge when striking. I personally would only use a ferro rod if I had to and I would not mind a slightly dulled area. But if I was using a ferro rod regularly I would probably carry a piece of hacksaw blade or similar for that purpose.