There are quite a few ways to empower archer skills actually.
I +5 increased damage for both Aimed Shot and Power Shot since those are the two big damage dealing moves for Archers.
After that, I haven't added a single empowerment point since because I can't decide.
But the most common ones are:
- SP Consumption for almost any skill, especially our poison ones. Archer skills take so much SP relative to our SP pool.
- Increased Duration for our poison skills.
- A few people use Decreased Cooldown for Nature's Protection but I don't think that's necessary. At all.
There's no need to Increase Damage for Poison Spells since they do so little damage anyway.