I don't think crushthrough is realistic, since when you block a weapon you do it at an angle, or approach form a certain vector that minimizes the impact. That is how a rapier can block a claymore consistently, using the right technieque. One does not block perpendicular to the impacting weapon unless there is no other choice.
However I AM a fan of weapons breaking. People would have to carry backup weapons then -- but it would have to be a rare occurence. +1 weapons could break unloomed weapons better, but not +2 and +3 weapons. +3 weapons could have a chance of breaking all other, but cannot be broken.