I have noticed respawning enemies, at least late in the game. Maybe you have to leave an area to bring back the enemies? I never really had to grind though. You level up pretty frequently just traversing the game normally. I think I was level 51 when I finished.
There are potions for bringing the meter back up on Ignatius, but I never really needed to do that. I rarely used any potions except in the last few battles. I always used Ignatius very carefully though. Sometimes you don't want to slow them, because you may have an oportunity to hit them in the red zone and interupt their attack. I did run out of Ignatius' meter on puzzles though.


