I'll allow it. But only a single (touch) attack on the round it was cast.
I don't see why not. Only a magus can cast a spell and weapon attack, but that's not what you are asking...
How I read the rules for this situation: a 4th level rogue with 18Dex, 10Str, two-weapon fighting, weapon finesse, Minor magic- something, and Major magic- Chill Touch, while flanking an enemy with rapier drawn, and an empty hand could:
Round 1 (Cast spell, move, and touch)
Touch +6(Chill Touch dmg) (+2 to attack for Flanking)
Round 2 (start two weapon fighting)
Rapier +4(1d6+0) +2d6 Sneak Attack, Touch +4(Chill touch dmg)
Round 3-4 (Rinse repeat)
The flanking bonus and TWF penalty in Round 2 would cancel each other out and you would only get Sneak Attack damage on your rapier because the chill touch damage is spell damage not Precision damage from a weapon.
(The Arcane Trickster class has an ability that adds sneak attack damage to Spell damage)
Edit: Just reread your question... I'm not sure about multiple touch attacks in the same round... I think that topic has been FAQed and changed many times and there are many threads that discuss how spells like chill touch actually work. I do know though that the above way of doing it works for chill touch...
Well, let me approach if fromt his direction...
While holding a charge unarmed strikes count as armed for purposes of not provoking AoO. As an unarmed strike is a melee weapon it can be used with iterative atatcks, it would normally provoke but thanks to the touch spell it doesn't. Since you can make iterative atatcks with an unarmed strike you should be able to two weapon fight with it. With the upside being that you only have to beat touch AC to deliver the touch attack, if you manage to beat full AC you could also deal unarmed strike damage.
Touch Spells in Combat: Many spells have a range of touch. To use these spells, you cast the spell and then touch the subject. In the same round that you cast the spell, you may also touch (or attempt to touch) as a free action. You may take your move before casting the spell, after touching the target, or between casting the spell and touching the target. You can automatically touch one friend or use the spell on yourself, but to touch an opponent, you must succeed on an attack roll.
Touch Attacks: Touching an opponent with a touch spell is considered to be an armed attack and therefore does not provoke attacks of opportunity. The act of casting a spell, however, does provoke an attack of opportunity. Touch attacks come in two types: melee touch attacks and ranged touch attacks. You can score critical hits with either type of attack as long as the spell deals damage. Your opponent's AC against a touch attack does not include any armor bonus, shield bonus, or natural armor bonus. His size modifier, Dexterity modifier, and deflection bonus (if any) all apply normally.
Holding the Charge: If you don't discharge the spell in the round when you cast the spell, you can hold the charge indefinitely. You can continue to make touch attacks round after round. If you touch anything or anyone while holding a charge, even unintentionally, the spell discharges. If you cast another spell, the touch spell dissipates. You can touch one friend as a standard action or up to six friends as a full-round action. Alternatively, you may make a normal unarmed attack (or an attack with a natural weapon) while holding a charge. In this case, you aren't considered armed and you provoke attacks of opportunity as normal for the attack. If your unarmed attack or natural weapon attack normally doesn't provoke attacks of opportunity, neither does this attack. If the attack hits, you deal normal damage for your unarmed attack or natural weapon and the spell discharges. If the attack misses, you are still holding the charge.
Melee Attacks: With a normal melee weapon, you can strike any opponent within 5 feet. (Opponents within 5 feet are considered adjacent to you.) Some melee weapons have reach, as indicated in their descriptions. With a typical reach weapon, you can strike opponents 10 feet away, but you can't strike adjacent foes (those within 5 feet).
Unarmed Attacks: Striking for damage with punches, kicks, and head butts is much like attacking with a melee weapon, except for the following:
Attacks of Opportunity: Attacking unarmed provokes an attack of opportunity from the character you attack, provided she is armed. The attack of opportunity comes before your attack. An unarmed attack does not provoke attacks of opportunity from other foes, nor does it provoke an attack of opportunity from an unarmed foe.
An unarmed character can't take attacks of opportunity (but see “Armed” Unarmed Attacks, below).
“Armed” Unarmed Attacks: Sometimes a character's or creature's unarmed attack counts as an armed attack. A monk, a character with the Improved Unarmed Strike feat, a spellcaster delivering a touch attack spell, and a creature with natural physical weapons all count as being armed (see natural attacks).
I think what the OP is asking is if a character has a held charge touch spell that has multiple uses (such as chill touch), but only one attack (because his BAB isn't 6+), can he two weapon fight to make two held charge touch attacks in the same round.
I would say no. I've always contended that when you cast your touch spell (and possibly get your "free" attack as part of casting) you also fix the appendage that you will use to deliver that spell. You don't get to put one charge in your left hand and one in your right and one in your tail and one in your prehensile hair and one in your boot-blade and one in your barbazu beard (or whatever else you're using to two-weapon fight with). You pick ONE method of delivery and you stick with it.
But what if I'm a Magus ? (I hear you cry). If you're a Magus delivering your touch spell through a weapon, the actual weapon doesn't matter (see the FAQ).
A magus could even use the spellstrike ability, miss with his melee attack to deliver the spell, be disarmed by an opponent (or drop the weapon voluntarily, for whatever reason), and still be holding the charge in his hand, just like a normal spellcaster. Furthermore, the weaponless magus could pick up a weapon (even that same weapon) with that hand without automatically discharging the spell, and then attempt to use the weapon to deliver the spell. However, if the magus touches anything other than a weapon with that hand (such as retrieving a potion), that discharges the spell as normal.
It seems to me the held charge is localized in the Magus's hand, and while he can change the weapon he's using to deliver it, he's stuck with the hand he originally put the charges in.
Now, I've been wrong before, so this isn't Gospel.
You can definitely make multiple touch attacks in a single round, but you cannot use two-weapon fighting with only chill touch. It's been clarified that when you cast a touch spell, it is 'held' on one hand (I read one limb, typically hand). It won't swap back and forth between two hands (nor can you have two cast at the same time, due to the rules on holding a charge).
So:
chill touch + rapier (TWF) - Good
chill touch + chill touch (TWF) - No good
chill touch + chill touch (iterative BAB attacks) - Good
You can definitely make multiple touch attacks in a single round, but you cannot use two-weapon fighting with only chill touch. It's been clarified that when you cast a touch spell, it is 'held' on one hand (I read one limb, typically hand). It won't swap back and forth between two hands (nor can you have two cast at the same time, due to the rules on holding a charge).
So:
chill touch + rapier (TWF) - Good
chill touch + chill touch (TWF) - No good
chill touch + chill touch (iterative BAB attacks) - Good
Ah, good point. Forgot about touch charges being specific to 1 hand. So, iteratives attacks you can then make multiple touch attacks with the spell. But you couldn't TWF with it because its only on 1 hand.
Makes perfect sense.
link to FAQ stating charges are held on a single limb?
I haven't seen that FAQ either, and I wouldn't trust anything from before the end of the Great Monk Fiasco. So it's GM discretion.
It's been clarified that when you cast a touch spell, it is 'held' on one hand (I read one limb, typically hand).
Definitely need a rules/developer quote citation on this. Touch spells are discharged when you touch something (whether that touch is intentional or accidental). If it were a specific limb then you could use your other hand for opening doors, retrieving items from your pack, pouches, etc, drink potions, use wands and so forth. Any citation you provide will be a direct contradiction of that, so it really needs to be a FAQ/errata to overrule it.
Holding the Charge: If you don't discharge the spell in the round when you cast the spell, you can hold the charge indefinitely. You can continue to make touch attacks round after round. If you touch anything or anyone while holding a charge, even unintentionally, the spell discharges. If you cast another spell, the touch spell dissipates.
It is unclear from this whether you can 'dual wield' your multiple charge touch attacks. (I would allow it).
Alternatively, you may make a normal unarmed attack (or an attack with a natural weapon) while holding a charge. In this case, you aren't considered armed and you provoke attacks of opportunity as normal for the attack.
You could definitely TWF making unarmed strikes - targeting normal AC.
I stand by my original post until rules/developer citation, FAQ or errata says otherwise.
I have not been able to find anything that indicates a touch spell is held in one specific hand, it's certainly not in the official FAQ, but i know some of the paizo staff sometimes answer questions here on the board. Perhaps it's from a post like that?
A link would be greatly appreciated.
+1
Even given that, Unarmed Strike is considered a single weapon (your whole body) with witch you can 2WF per specific FAQ. So you CAN actually 2WF with only your right fist. And deliver a touch with each attack.
I'm not so sure Dekalinder, TWF uses a primary and off hand attack even with unarmed strike. If a held spell is considered associated with a "hand", then you can't unarmed TWF the touch spell .... unless you are a monk using flurry who specifically calls out the TWF with one weapon.