Just a thought - blocking a powerful blow with a heavy weapon could lead to breaking the block - the defender would not simply be strong enough to hold against the blow and he would only slow the attacking weapon down, suffering partial damage.
This would apply only for swings, because when blocking a thrust, you actually don't stop the force of the blow, but push the weapon aside, allowing the tip to travel past your body.
The relative weights of the weapons would have to be considered (it's much easier to block a two-handed sword with another two-handed sword than with a shortsword). Also, relative strengths of the opponents would have to be measured. It would be possible that a very weak person could not block much stronger opponent at all, which is IMO realistic (peasant women).
This would apply only for swings, because when blocking a thrust, you actually don't stop the force of the blow, but push the weapon aside, allowing the tip to travel past your body.
The relative weights of the weapons would have to be considered (it's much easier to block a two-handed sword with another two-handed sword than with a shortsword). Also, relative strengths of the opponents would have to be measured. It would be possible that a very weak person could not block much stronger opponent at all, which is IMO realistic (peasant women).