Two perk Ideas. One based around Mob killing, the other around Ore/Tree nodes
Hunter line
Give % Chance of dropping more components from enemies (Leather, teeth, rare materials)
Every 10 harvesting levels add 20% to common materials to get a bonus 1-2 (Luck based?) up to 100%
After 50 Harvesting add a 10% chance to find rare materials more often (Gimpassa shells and such) or have a chance for materials to drop two instead of one
Prospector
Give a 5-10-15% chance to increase the quality of a node you are scanning every 10 levels in harvesting
This would mean at 100, You would have a 50% chance of a tier increase, a 100% chance of a tier increase, or a 100% chance of 1 tier increase and a 50% chance to increase the tier again.
That ^ Perk could also lead to Tier 4 or even 5 Ores if you find and get lucky on a high-tier node