Hi! Reading through Chain of Command I think I found a typo: the parrying section (pg. 187) reads "The ability of a defender to parry depends on how much greater their weapon class is compared to that of their attacker", but it should be "The ability of a defender to parry depends on how much lower their weapon class is compared to that of their attacker".
Also, the weapon breaking in case of a kill score is the defender one, not the attacker one.
The idea being that only similar weapon (or lighter and faster ones) can engage in parrying, with the added possibility for the defender weapon to break, denying an otherwise killing blow.