Would it be too much of a stretch for the APG feat Point Blank Mastery as taken as a Ranger bonus feat for archery to apply to thrown daggers? I have this idea in my head for a circus troupe and a furry fantasy world and using the background option from Tome of Secrets to build a ranger who is at turns a canine clown and a knife thrower. Not necessarily at the same time but there are other factors for that as well.