Those wearing cloth armour had best have some way to turn their offense into a better defense! The lightest form of armour before one can be considered naked, cloth grants a bare minimum of protection -- more from the elements than from blade or spell. At one time, many spellcasters of Sosaria and Britannia were bound by the strictures of their professions from wearing any armour heavier than cloth; the reasoning behind these early prohibitions are largely unknown in later times.
Seen in use between Ultima II and Ultima VI, cloth armour was apparently reduced to the status of non-protective clothing by the time of Ultima VII.
At the time of Ultima V, cloth armour was given a "1" relative protection rating, compared to a "2" for leather armour and "7" for plate.