Hi Paolo,
Its a nice thing for sure! I'm not familiar with them, so I'm not sure how the steel/iron is produced.
So I'm just gonna throw some thoughts out there.
Could the steel be produced from a mixture of salvaged/reclaimed ferrous items which may result in a final product with 'hard spots'?
I know that this can be the case even with industrially produced western steel from recycled sources, I wonder if the larger 'spots' which look almost like a birds eye or raindrop pattern could be something to do with an accidental mixture of steel grades not completely mixing in the smelting process.
How oxidised was the surface before you etched it?
Is some of the pattern from cleaning out the pitting?
If you can remove the blade you could 'recut' an area of the tang to completely flat and polished then etch that area and see what pattern emerges?
Edit:
Do the wootz style patterns diminish where the blade looks to have been filed (As in where the surface has been cut back)?
Just been comparing it with bits of steel I've got laying around, sadly I've no actual 'wootz' but I've got some pattern welded.
