A pair of apparently finely-made armored boots provide +1 AC. Apparent value is 400 GP (DC 20 to realise that the boots are a cheap imitation).
The boots remain sturdy and comfortable until combat, when they fall apart upon the wearer's first turn, cutting into the wearer's legs, dealing 1d6 damage per leg.
If fighting on difficult terrain, 1d4 damage is dealt with each 5-foot step, since the character is now barefoot.
Used these in my game last night. Player still hasn't caught on, but she's starting to figure it out.
On solar day 18.2019 by Roamer