Beautiful etched shamshir, 19th century. This kind of blade would not be much fun to carve due to it being wootz, but using resist/etch to create a bit of relief would be relatively easy and much more efficient. There are many documents showing etching of pattern welded steel in gun barrels and swords. From the old manuscripts about forging gun barrels from strips of steel and iron, the final steps before honing the bore involved soaking the barrel in a mild acid in a hole in the ground. There were many different formulas for etching solutions. A 1:1 mix of nitric acid and water will do a deep etch on hardened steel in a short time. 8:1 water/nitric acid will do a smoother etch over a longer period of time. The etch resist can be as simple as wax, but something thinner is desirable for painting on a pattern like this one.