We all know that 2 handed weapons greatly out damage 1 handed weapons at higher levels. So I was wondering how this small change would affect the balance.
Attack penalty adds when you use the same hand more than once in combat. As an example a 2 handed swords is used to attack with the first action. Any additional attacks would have a -5 penalty (as both hands where used). The second and third attack would be at -5 and -10 as usual. But when 2 1 handed weapons are used the first attack with weapon 1 has no penalty. A second attack with weapon 2 has no penalty, but a third attack with either hand would be at a -5.
This could also allow for shields to stay raised from turn to turn without the need to lower them, because the sword and board player would have a natural penalty to offset the shields advantage. As they would make all 3 attacks with the same hand.
While this won't make +5 1 handed weapons hit harder than +5 2 handers, it will increase thier overall damage per round making the 1 handers closer to the damage of 2 handers.