Hi
Nice blade.......  you know there it could be an english blade...
have you heard of shear steel........ some of this shear can really reallly have a lovely wootzy look.....   
here is what i mean......   Ray Richards forged out some old saw mill blades into knives....   and then etched them..........  
Look at the 2nd knife he made  ( about the middle of the post ).......    see the swirly pattern on that shear steel.......   
http://forums.dfoggknives.com/index....hl=shear+steel
it maybe that this blade might have a hint of that......... who knows.... or maybe its just the rust that made a pattern..   ???    hard to tell with photos
Greg