So, I'm levelling one of my mules out in La Theine, and come across "BirdEgg" on the ground (at the southern spawn point). Never heard of it before, don't remember seeing Nihni in ANY of the NM lists so it didn't really mean much to me. I clicked on it, got an egg, and all of a sudden, the text comes up and pop goes the NM... Being 20WAR/10MNK, I expected to die, triggered Mighty Strikes, and by the time it wore, the NM was down to about 50%... I wasn't far from 50% myself, tho it wasn't attacking much faster than a normal Akbaba in the area, just hittin for 10+ per hit. I countered a few, WSed a few times, and poof, I had myself a Van Pendant, which beats the hell outta the stupid Justice Badge I'd stuck on the character for the DEF boost... got 52 exp as well with my Chariot Band active (yes, this is a mule, and I went cheap with him, so those givin me crap over the gimp ring or neck piece can sod off).
No clue as to 100% drop rate, I've seen plenty of other R/E drops NOT be 100%, lame as that is. Made me a happy camper tho, for once. If I'd'a been actively seeking the NM n drop, I'd'a prolly never seen it, or died, or not gotten the drop... :p
Be well n stuff