have you current gear with proper attrubutes? while leveling there are sometimes opportunities to get a whole new set of gear from some NPCs
i once had a the problem i had for example a lot of crit chance on a sorcerer which did not profit from it (needs double atack)
reinc debuff means you do less dmg but it still should be possible so i assume you forgot something...?
look at astral academy the girl NPC "naia windina" at the anvil, does she have a gearox for you?
yeah the gear you get at lvl 75 is very bad,especially with the debuff.
i had to be cautious with every npc i fought until lvl 79 and suddenly i can't deal much dmg to any npc.
i tried adjusting stats but i had very few insignia from leveling i was about to give up when i remembered i can turn off the buff and it really helped