That said, yes you can tell the difference between a weak strike and wear. But you can't do it based on luster because if there is wear, there is no luster; and if there is a weak strike in a given area, there is no luster in that given area either. Weak strike and wear have that in common which is why so many get confused by the two different things. And it is also why many, even the TPGs at times, interpret what is really wear as a weak strike and thus over-grade the coin. The way you differentiate weak strike from wear is by looking very closely at the area in question. The surface of a weakly struck area will be kind of rough, bumpy even. While the surface of an area with wear will be flat and smooth. And on coins with little toning, or no toning if the coin has been dipped, there is a slight color difference between a weak strike and wear. Both will be a shade of grey. But wear will be a darker shade of grey than a weak strike will be. You have to get used to that, experience it, see it numerous times, to be able to recognize it when you do see it. It's tough to recognize the color difference, but the difference is there.