Suggestion, If I may,

1. Increase enmity on Voking related skill (by large percentage)

2. Increase enmity on defese/evade related skill ( small percentage)

3. Increase enmity on attack related skill (both melee/magic) ( small percentage )

4. Increase enmity on direct damage (both melee/magic) ( by large percentage)

5. Decrease enmity on cure/curaga (by large percentage)

6. Emphasize more on enmity control skill/trait/equipment ( with the enmity in the text description)

7. Add enmity reduction slowly over time if turn to passive mode or do nothing.

Now, you can make any boss/NM as hard or as much AOE, or as tricky as you want.
All class balance. (Pretty much)