I admit, the nails aren’t that big of a problem for me. Other stuff bugs me a lot more 🙂
As to the editing the book. In general a book shouldn’t be edited after release, of course. However, sometimes you only have the choice between having a story that contradicts itself and fixing the released book so the story doesn’t contradict itself. Considering fixing the story a little will lead to better reviews and as such better sales, I think fixing the book as soon as the readers brought up the contradictions is paramount to good sales. But ultimately it’s up to you what to fix and when, of course.
P.S. Though you could make the nails shorter and thus have somewhat more or less believable picture both when Tom uses fists and when he uses fingertips.
P.P.S. Also, karate chop should probably be named “knife hand”, though there you have to choose between using a well known phrase that is associated with an unrelated martial art and a proper name that is less well known. Tough decision too.