Off hand, Main hand does it matter?

[Kylas]

If your BaB is 6/1 are you allowed to use your off hand for the second part of your full attack without incurring TWF penalties? E.g great sword/armor spikes. In the next round if i use only my off hand do i incur any penalties? e.g. armor spikes/armor spikes.

And Im assuming whatever rules are explained apply to someone wielding to daggers or 2 pistols and also don't have TWF feats.

 

[Elethiomel]

That depends entirely on how you interpret the term "Fighting in this way" under the two-weapon fighting rules.

Here's the quote from the Rules Compendium:

If you wield a second weapon in your off hand, you can get one extra attack with that weapon when you make a full attack. Fighting in this way is very difficult, however, and you take (two weapon fighting penalties).

If you interpret "Fighting in this way" to refer back to "get one extra attack with that weapon when you make a full attack" (which I do) you can take iterative attacks with any manufactured weapon (or unarmed strike) you wield, in any order you choose.

Others interpret it to refer back to "If you wield a second weapon in your off hand", where "wielding" means holding a weapon ready to attack (so if you hold to this interpretation, you need to take TWF penalties in order to be able to even AoO with the second weapon).

 

[Runestar]

Yes and no.

Using your example, a fighter with bab +6/+1, wielding a longsword in his right hand and a dagger in his left can make an attack with the longsword at +6, then with his dagger at +1, without incurring the TWFing penalties. So you get +str mod to damage on both attacks.

However, the PHB apparently has this entry about fighting with your off-hand incurring a -4 to-hit penalty, though I usually just waive it in my games. It shouldn't apply to armour spikes though, since you technically don't wield them in your hands.

In the next round if i use only my off hand do i incur any penalties? e.g. armor spikes/armor spikes.

No. You can freely declare the armour spikes to be your primary weapon or off-hand, depending on your preference (and there would be no reason to not declare it as your primary weapon if you are attacking solely with it).

Though it is typically more advantageous to attack with your greatsword as your primary attack, and spikes as secondary, since you get +1.5 str mod on your greatsword attacks.