They confirmed we'll be able to sign crafted items, but I assume that only means a "[name]" in Latin characters as part of the item's menu description, a la FFXI.
I think it's a fantastic idea to be able to engrave metal as you suggested, but I have no idea how hard it would be to apply that to model textures in a way that would look quality without forcing too much extra data to need transmitting. I imagine simply overlaying text on top of existing textures wouldn't be too hard but I can see that coming out maybe a little fakey looking... I doubt we'll see such a thing happen.