So assuming you do find a "pretty good" legendary of the type you need, would 3) be better than 2), even though you can't whetstone-upgrade it?

Also, I guess 1) is worse than the others? I'm basically trying to figure out if it's worth it to invest that extra point in Blacksmithing for the extra whetstone boost.

Actually, come to think of it, if you plan on 2), you're guaranteed to have a weapon at your level every level, so maybe that's ideal?