You can sharpen anything, but it will retain an edge only if it has been hardened and tempered. Most of the "pakimascus" I've handled lacks enough carbon to harden or the heat treat is skipped and they don't hold an edge. So, to be "real" they have to be hardened to be a real knife instead of something just shaped like a knife.
An additional note of caution about foreign "damascus". Any time you see cheap price on this stuff be skeptical. I have had to have dealers take Pakistani and Chinese "damascus" knives off their table at our show, we have very strict rules on what goes out on the table, when I showed them some of their knives had the exact same pattern on the blades. It isn't possible with actual pattern welded steel for the pattern to exactly match once you grind the blade, down to the shape of the individual pattern elements, so that you can line the pattern up from one knife to the next. Each real damascus knife is unique in pattern when ground. So, if you're buying at a flea market or show and the dealer has several of the same knives in "damascus", lay them out side by side and look for a match in pattern. If you see that, walk away.
Online, if you see "damascus" cheap, apply the "too good to be true" axiom.
