Compare the passage from 1e AD&D on two-weapon fighting.
Attacks With Two Weapons:And just for kicks, here's what 1e AD&D says about parrying as well.
Characters normally using a single weapon may choose to use one in each hand (possibly discarding the option of using a shield). The second weapon must be either a dagger or hand axe. Employment of a second weapon is always at a penalty. The use of a second weapon causes the character to attack with his or her primary weapon at -2 and the secondary weapon at -4. If the user’s dexterity is below 6, the reaction/attacking Adjustment penalties shown in the PLAYERS HANDBOOK are added to EACH weapon attack. If the user’s dexterity is above 15, there is a downward adjustment in the weapon penalties as shown, although this never gives a positive (bonus) rating to such attacks, so that at 16 dexterity the secondary/primary penalty is-3/-1, at 17-2/0, and at 18-l/O.
The secondary weapon does not act as a shield or parrying device in any event.
Parrying disallows any return attack that round, but the strength "to hit" bonus is then subtracted from the opponent's "to hit" dice roll(s), so the character is less likely to be hit. - 1e AD&D PHB, "Melee Combat," p. 104I've been thinking about this a bit in the context of running a 1e AD&D swashbuckling & sorcery campaign. Looking at the original rule on fighting with two weapons, I think Paul's rule could slot in right beside it - either attempt to gain an extra strike at a penalty, or attempt to use both weapons to gain an advantage such that one of them will find its mark. I like this, because it adds to the feel of fencing which cape-and-sword games attempt to capture.
To really capture that feel, perhaps there also needs to be more choices on defense as well. Trollsmyth's shields must be splintered house rule works very well for battles involving bastard swords and maces, but it doesn't feel quite right for combat fought with a buckler and a basket-hilted broadsword. While I don't like the idea of 'lightly armored fighters' gaining an advantage to armor class to compensate for not wearing armor in D&D, perhaps allowing a main-gauche to provide a +1 to armor class, but limiting it to defense against swords and daggers only, might work. Another thought is, rather than raising armor class with experience, the Duelist gets to use Dexterity in place of Strength when parrying.
In any case, I like Paul's rule and I can see it finding a way into my campaign.