
avr |

Item mastery feats then. The obvious problem is that archery takes a lot of feats, a style takes more, you'll need at least one for the iron caster, and rage requires at least one level in a class which doesn't provide much in the way of bonus feats. You're not going to get everything online for a while.
Since you need a lot of feats this will be mostly fighter levels. One level in savage technologist barbarian gives you the most useful form of rage for an archer, +Str & +Dex. You probably want the base fighter because armor training is useful for a high-dex archer, and you need weapon training for the iron caster. Fighter 5 / Brawler 1 / Barbarian 1 / Fighter +X makes sense. Human for the bonus feat. That might work out as
1: Point blank shot
Human: Weapon focus (longbow)
Fighter 1: Precise shot
Fighter 2: Rapid shot
3: Empty quiver style
Fighter 4: Weapon specialization (longbow)
5: Combat stamina
7: Manyshot
L8/Fighter 6: Clustered shots
9: Stabbing shot
L10/Fighter 8: Empty quiver flexibility
11: Deadly aim or greater weapon focus, depending on whether accuracy or damage has been more of a problem thus far. Or improved precise shot if cover's been a problem.
That's focusing more on archery. If you want a bunch of item mastery feats rather than just those obtained via advanced weapon training/item mastery option then you'd need to sacrifice or delay some of those archery feats. After those feats there are still more you can take for archery BTW - improved critical & critical feats, far shot or circuitous shot - it really can take every feat you have.