As a casual non-leagal observer, it seems to me that the husband shouldn't, and couldn't, be charged with anything. It would be very difficult to prove intent, unless he told the clerk who sold him the knife that he was going to take it home to murder his wife. Even if he bought it with the intent to kill the unlucky woman, his intent may have changed between the time he bought it and the time he left it on the dresser. If he had left the knife in a dangerous position, he might be charged with reckless endangerment. But he just left it on a dresser. The fact that he "changed his mind," as stated in the question, is very significant. Apparently he didn't even have the intent any longer.