This is Jeff's argument to go to 1 single skill. This is right, nobody learns to attack and not to parry (or to parry and not to attack), but the experience is a completely different matter. My personal experience as a fencer was that I was quite a good attacker (probably above 90%), but not a good defender (around 60%). I lost during a french national championship finals with ... 0 points because my opponent parried all my attacks, and I could parry only some of his.
The separate skills, the moves integrated with the SR, the number of actions per round, the special maneuvers and effects (disarm, knockback,...), the 10 SR round, ...