Hypersmurf said:
It's a limitation caused by wearing medium armor.
But one is not wearing medium armor when wearing Mithral Full Plate.
One is wearing heavy armor "as if" it were a medium category. "as if" and "are" are two different things.
Mithral Full Plate looks like heavy. It sounds like heavy. Except for weight, it feels like heavy. It's AC (with also is not a limitation of wearing heavy) is like heavy.
Only
limitations caused by wearing heavy armor are limitations that apply to heavy armor.
AC 8 applies to Full Plate. It does not apply to Medium Armors. Is this
ALSO a limitation of medium armors? No. It is an
advantage of Full Plate Armor, just like another advantage of full plate armor is that the greater iron ward diamond works with it.
A limitation in some other type of armor is not a limitation in heavy armor.
"John cannot legally vote for the President in the U.S. until he is 18.
John looks 16 and has the muscle reflexes "as if" he were 16 year olds.
If John is 18, he can still vote for President because although not voting at age 16 is a limitation of age 16, it is an advantage of age 18."