"Blunt Trauma and Edged Weapons" is an optional rule reducing the effects of cutting damage on amoured targets first published in GURPS Low-Tech p. 102 in December 2010.
This rule is similar to blogger tbone's house rules for Edge Protection. Edge protection was proposed for GURPS third edition revised, and had been converted to GURPS fourth edition by January 2007:
They allow gamers to better represent strong but flexible armour such as mail.