Found a handful of NM's, Duke Folacor, on the hillside in xarcabard G-7. Seems to like using souldrain, and endrain on hits by the looks of it. No drop, 58 gil >.>;
Found a random mandy NM in yuhtunga jungle, in the center ish area, no drop from him.
Ran across 2 different undead type impossible to gauge enemies in zi'tah north of the outpost. Skeleton scuffler took damage from blunt (clubs), but didn't take damage from my npc's slashing attacks (sword). Ghost impossible to gauge enemy's to the east of those scufflers. Holey somethingorother; didn't take any damage from my clubs, nor from banish/cure spells, however seemed to take (albeit minor) damage from npc's sword attacks.
Those Zi'tah NM's seem to dissapear after a short period if you don't kill em. If I was to place a bet, I'd say they're part of a quest, given their odd damage resistances, Impossible to gauge status and the multiple/quick spawn times.
*EDIT added pictures*