This is quite interesting topic for hunter (or any ckass) and group basics.
First - using lvl59 First Age Bow is really holding you back here. lvl70-74 Third Age bow will have significantly higher ratings, I may be wrong but it should be arround -30. So, even a third age, it will do more damage and will lower your aggro more. My basic rule of swapping Legendary weapons is to change it when the initial DPS of the new bow is higher than maxed of my old one. Also, I will advise you to go for Focus skills threat down instead of Induction - the reason is Focus skills usually hit harder and crit more and need their aggro kept low
Second - aggro works in misterious ways.... or not actually. Even if you give your champ mate some time, his way to keep aggro is by doing damage to the target. In the very moment you do more damage than him (even if startign later) you will have the aggro.
Third - don't hold yourself back! You are a hunter and what hunters do best is hell of a single target DPS. The harder you hit - the less time will have your enemy to attack you To hit harder you need to stack more Agility, and the good thing is Agility gives you tons of evade, so your enemies will have hard time to hit you, it also gives you parry (the same ammount that Might will give) and crit (so you will hit even harder). Talking about stats we come to:
Fourth - Leave Might to champs. What you really need is (in my personal order) - Agility, Vitality, Mitigations (from virtues), Fate, Crit and Physical Mastery. Since 1 Agility = 10 Physical Mastery you need to calculate if it's better to have an item with less of a stat but tons of pure physical mastery.... and when it's not. Same goes for Vitality/Morale and Fate/Crit/Power regen.
So, basically - do not use too old weapons (it's reasonable to change em every 5-7 levels untill you reach cap), stack Agility and unleash hell on your enemies.
I hunt. I kill.
Warden by destiny, Hunter in the heart.