Two weapons and reach

[Elder-Basilisk]

Why would a character need to take the TWF penalties for making an AoO with his off hand?

Ordinarily, a character with Ambidexterity but who has multiple attacks may make his iterative attacks with either weapon without penalty. For instance, Drizzt has (IIRC) a +3 Frost Brand Scimitar and a +5 scimitar (off hand). If he comes into melee with some advanced creature that has 25/+5 DR, he can make one of his 3 iterative attacks with the +3 Frost scimitar, notice that it does no damage, and finish the rest of his attacks with the +5 scimitar without taking the TWF penalties. Only if he chooses to take an extra attack (or more with Improved TWF) with the off hand does he suffer those penalties.

Based on that, I see no reason that a character wielding a longspear in one hand and a sword in the other (or more likely, wearing spiked armor. . .) couldn't take an AoO with the sword without incurring TWF penalties. After all, he has not gained an extra attack through this exercise--he has simply expanded his threated area at the cost of a considerable amount of cash and feats and the inability to use a shield (this is all less costly for the spiked armor wearer but still not over the top. . . .)

 

[Christian]

That was my thought as well, E-B. Two points I'd like to add to prevent any misunderstanding:

1) A character can't wait until after his first attack to decide whether to use two-weapon fighting. An Ambidextrous character can use either weapon for any attack without penalty; but to take two attacks at the highest BAB, this has to be declared before the first attack roll is made. (I know you didn't say otherwise, but it may not have been clear to every reader.)

2) If the character does use two-weapon fighting on his round, the penalties (typically -2) apply to every attack made during the round; I suggest that this should apply to AoO's made before the character's next turn. It's not entirely clear that the rules demand this, but it seems a sensible interpretation to me ...

 

[Elder-Basilisk]

2) If the character does use two-weapon fighting on his round, the penalties (typically -2) apply to every attack made during the round; I suggest that this should apply to AoO's made before the character's next turn. It's not entirely clear that the rules demand this, but it seems a sensible interpretation to me ...

This is my understanding as well. Typically, effects that apply "until the end of the round" apply until the beginning of the character's next round.* This is how one round duration spells (command, daze, etc) are interpreted. It is also how I have always interpreted power attack and expertise. I believe that the penalties for those feats and for TWF would also apply to opposed attack rolls such as are required by sunder or disarm attempts (making either feat a risky proposition against someone attempting to sunder or disarm your weapon).

*The rules are not exactly clear about the effect of haste on this penalty but I have always ruled that haste was irrelevant to the start of a character's next turn.