Undead status and Near Fatal attacks

Has anyone ever noticed that Near Fatal attacks (like Cyclonic) work on ALL undead monsters in vanilla FF3?  I did some digging around today, and discovered what I think the reason is. Basically, monsters are only immune to near fatal attacks if they are immune to instant death attacks (which I'm sure everyone knows).  The block "Near fatal" check box in FF3USME does nothing.  However, if a monster has the undead status but is not immune to instant death attacks, near fatal will work.  The problem here is that the game also has a bug in which monsters with both the undead status AND protection to instant death spells will cause weapons with the "randomly kill" flag (like the assassin dagger) to not display the "X" kill animation.  Instead, you hear the "half dead" sound effect without any animation at all.  I'm guessing this is why vanilla FF3 does not have any undead monsters with immunity to death spells; they were probably aware of possible bugs with the undead "re-appear" animation.

In my mod, I would like to give certain undead monsters immunity to near fatal attacks, but there doesn't seem to be a way to do that without causing the bugs mentioned above.  I did some searching and thought this fix would work, but it appears to be related to something else (in fact, I am not exactly clear what that patch does).  I would not be opposed to giving undead monsters immunity to near fatal attacks completely if there is no other solution, but I am curious if anyone knows of a fix to this problem!