By rat tail tang, he means does the blade of the knife narrow down to what looks like a 'rat tail as it extends into the handle, the 'Tang' is the part that enters the handle. Does the 'tang" connect to a butt plate or nut at the back of the handle, or how is it secured? Also, you say 'engraved', but it looks more like 'patterned steel', otherwise known as 'Damascus steel', where the pattern in the blade is derived by making a 'sandwich' of high and low carbon steels, and 'forge welding' them together, and then folding the billet and hammering it out again, 'quenching' the hot steel to give it a very hard, yet flexible, "TOUGH" blade that takes a superlative edge, and then keeps it! Done properly, you get the 'best Steel in the world' by some lights, and by applying a light acid etch after forging, the beautiful patterns the steel is noted for emerges from the background and forms the basis for gorgeous weapons.