No, computers aren't very good at creating unique things without explicit instruction on how to do so. But they are very good at replicating things to an exacting standard. In the case of a painting, a computer could probably make an exact replica of an already existing painting far better than any human artist could.

In the case of knives, a computer could make a copy so exacting that it would be indiscernible from any of the knives this guy produced if given the instruction and materials to do so. The only thing that would give the computer made knives away would be that they would be too perfect (if perfect is measured by how close it falls to the original), while the knives produced by hand will all have inconsistencies because they were made by something that isn't precise to a micrometer.

Speaking of which, that's part of what I think drives the hand-made movement: you're buying something unique. Even if that particular artist made a hundred of them, there are no two exactly alike.