OBX,
String Blur in my opinion is the aimer's rear sight.
We had footage of a string blur discussion ready for the film, but decided to cut it for follow-up film "The Push 2" as the topic was a little advanced for the content being discussed.
One pitfall some fall into is tuning their arrows to support windage impacts. The key is to tune your bareshafts to impact with your fletched shafts regardless of where the fletched group is impacting in comparison to your intended impact point.
In your case - tune your bareshafts to impact with your fletched shafts, even if your fletched shafts are hitting 6" left of the blue spot.
Once that is accomplished, you can simply adjust your string blur (read that rear sight) to bring your groups into the blue spot.
When you're at a comfortable anchor point, take a second and notice where the string is located in your peripheral vision in comparison to your riser. Assuming you're a right handed shooter, your string blur is probably 1" to the right of your riser.
If you want to bring your group to the right, but keeping your tip on the blue spot, adjust your string blur so it's lined up with the right side of your riser. (or whatever landmark you want to use)
At first it will be kind of weird because essentially you're paying attention to your string blur and your arrow tip at the same time, but eventually it becomes natural and you don't have to worry about string blur anymore because your anchor point and head position needed to bring your string blur (rear sight) in line will become natural and normalized.
So if your bareshafts are grouping with your fletched shafts, don't adjust your tip weight or arrow length any further. They are tuned. Don't adjust them to adjust your impact point at the target because you're detuning your set up.
Simply utilize string blur to adjust your windage left and right with your tuned arrows.
Impacting left, Bring your string blur closer to your riser (move it left)
Impacting to the right, bring your string blur to the outside of your riser (move it right)
Reverse that for a left handed shooter.
Hope that helps.