Plate Mail of Etherealness is seemingly normal +5 armor, but if a
command word is spoken, the suit enables its wearer and all non-living
items he or she wears and carries to become ethereal,
just as if oil of etherealness (q.v.) had been used. While in the ethereal state the wearer
cannot attack material creatures. A phase door spell will negote the
ethereal state and prevent the armor from again so functioning for 1 day.

There are 20 charges placed upon plate moil of etherealness, and, once
used, they cannot be replaced or recharged. Furthermore, every 5 uses
reduces the class of the armor by 1, so if 5 charges ore used to become
ethereal the ormor is +4, if 10 are used i t is +3, +2 if 15 are used, and
only + 1 if all 20 are exhausted.