In variants that print messages such as “Foo’s [armor piece] deflects your attack”, extend this system to monsters that have relevant defensive body parts even if they’re not wearing armor. Do this by crediting them with an appropriate amount of fake AC when determining what string to use for “[armor piece]”. Then players that miss monsters instead get messages about the monster’s natural armor preventing them from doing any damage.

The inspiration for this is EvilHack’s giant turtle, whose AC of -8 prompted many inexplicable “miss” messages for such a large and slow creature.