Right now the way the system works is that it takes the lower score of a bow/arrow when determining the aiming speed and turn/walking penalty on a bow.
Meaning, if you have a 160 vitality and essence bow, and a 10 vitality and essence arrow, you will aim the same speed as if you were using a 10 vitality bow, and have the same penalty as if you were using a 10 essence bow.
The same works the other way, a 160ql arrow and 10q will aim as if the quality was 10
My suggestion is that it takes the average of these two qualities when determining vitality aiming and the turn/walking penalty, meaning a 10q arrow with a 160ql bow would aim and turn as if an 85ql bow.
Substance is not related, as damage is calculated with the sum of bow and arrow (10q bows add 80, 40q add 160, 90q add 240, bone arrows at 10q add 100, 40q 200, 90q 300, and so on)