Note to Mages

[Nvr]

Are you sure they arent mistaking it for this: http://wiki.ffxiclopedia.org/wiki/Manananggal
Miclantecuhtli absorbs damage unless casting, Qutrubs on the other hand do take double damage. They both have names starting with M, found in same map, could be easy mistake.

I have not researched it at all. I was just responding based on several other posters comments.

Here is the wiki

Low Physical Defense

Seems to take enhanced damage from physical attacks, but only while casting. If attacked while it's not casting, it will recover an amount equal to the normal damage of the hit.