Problem: there is very little PvE character progression in the game right now. You PvE for 10 hours and your character can be 80% of the way there which is great for the PVP aspects of the game but not so great for PvE where you can feel almost no progression when killing monsters.

Solution Part 1: Some skills that slowly level up from use but are quite impactful for archery, melee, magic damage, and damage taken(right now higher mobs just put out so much damage regardless of your gear/stats).

Solution Part 2: New specs you can opt into. Similar system as destro and mage killer but entirely separate from PVP.
Some examples:
Tank: Deals 10% less damage, deals 50% more threat( is threat a thing with mob AI? No idea), 20% damage taken reduction from mobs only
Archer: 20% more arrow damage, 10% less magic/melee damage.
Mage: 20% more magic damage, 10% less archer/melee damage.
Berserker: 20% more melee damage, 10% less magic/melee damage, 20% more melee damage taken
Healer: 20% more healing if target has taken PVE damage recently. 10% less damage, 10% more damage taken.