If this exists probably it should be relative on weapon x weapon, like a sword hitting a sword won't do much of a damage, but now a maul against a sword in upper block probably would bend/break it and kill you on the same hit.
WotR have some pretty decent hitbox, and my weapon did broke there like 4 or 5 times, when i was defending upwards, against an axe or anything heavier than my greatsword. But again, people there is more occupied spamming than defending, since defending doenst gives you any bonus and you probably can lose your weapon in the process. Close, but no cigar