My question is do the Improved-TWF and Greater-TWF feats grant additional attacks to the second/third off hands? Put another way, does the "special" section of Multiweapon Fighting extend to the other TWF tree feats.
there are a lot of threads debating how to handle fighting with two falchions for a 4-armed alchemist, but as far as multiweapon fighting goes, you can't apply it to a multi-armed alchemist, unfortunately.
Benefit: The alchemist gains a new arm (left or right) on his torso. The arm is fully under his control and cannot be concealed except with magic or bulky clothing. The arm does not give the alchemist any extra attacks or actions per round, though the arm can wield a weapon and make attacks as part of the alchemist’s attack routine (using two-weapon fighting). The arm can manipulate or hold items as well as the alchemist’s original arms (for example, allowing the alchemist to use one hand to wield a weapon, another hand to hold a potion, and the third hand to throw a bomb). The arm has its own “hand” and “ring” magic item slots (though the alchemist can still only wear two rings and two hand magic items at a time).
so, you can hold 4 weapons, but you can still only attack with 2 of them. if you want to get more attacks, take the feral mutagen discovery, since you can combine natural attacks with normal attacks at a -5 penalty (-2 with multiattack).
No, you still get 2 claws. But you can attack with natural weapons at the end of a full attack as secondary natural attacks (-5 to hit, half str mod to damage). The (usual) problem with claws is that you need those same hands to wield your weapon, and thus cannot also use the claws that round.
With Vestigial Arms, you have two hands to hold a weapon or weapons for all of your iterative attacks, and then have the claws on different hands and thus available for use.
It's no different in concept than using armor spikes, unarmed strike, or something else for your iteratives, and then claw/claw/bite from feral mutagen. It's just...weapons you can hold in your hands tend to be better than unarmed strike and the lot (can get a big ol' greatsword for 1.5x str mod to damage, or TWF with shortswords, and so forth).
All of those options are RAW legal. Note that in the case of TWF w/ 2 falchions, the 2nd one will still only be getting 0.5x str mod to damage, because that's just how the TWF rules work.
What is your strength going to be like? If it's high, you might want to actually 2H a Falchion and then add the claw/claw/bite, saves you some feats. Or possibly even just stick with claw/claw/bite only. Having them all as primaries is nice.
I suppose it also matters how often you expect to be able to sneak attack...
The arms can be useful for other things. I currently have a dex-based viv. alchemist. I took a tentacle instead of arm, but basically the same deal there. I use the tentacle to wield a darkwood heavy shield (no ACP = who cares you're not proficient?). Spending a feat on Extra Discovery for +2 AC, going up to as much as +7 when I enhance it, it totally worth it to me.
You should be trying to obtain a CL 20 or as high a CL as possible potion of Greater Magic Fang to use w/ Alchemical Allocation to buff each of your natural weapons. You could also do this for your unarmed strike if you wished.
If you can't buy one, you can actually make it yourself. The requirement for a potion of GMF is CL 5 normally, or 7 in your case...the min. CL needed to cast the spell. Just use a higher DC to make a CL above your own actual CL. The rules allow for this, you just set the spellcraft (alchemy for you) DC to 5 + CL. So a CL 20 potion would be DC 25, pretty easy to make.
Can you break that down for me? I'm working on an alchemist right now as well, and I might be crazy but I don't see any discoveries that grant ACThe arms can be useful for other things. I currently have a dex-based viv. alchemist. I took a tentacle instead of arm, but basically the same deal there. I use the tentacle to wield a darkwood heavy shield (no ACP = who cares you're not proficient?). Spending a feat on Extra Discovery for +2 AC, going up to as much as +7 when I enhance it, it totally worth it to me.
The tentacle holds the shield. This allows me to still have my hands for claw attacks. The shield provides +2 AC, up to +7 if enhanced. AC I would not normally be able to enjoy if I wanted to fight with both hands.
That's...about it, really.
And Vestigial Arm would work just as well. I just was going for squick factor and wanted my character to be as grotesque looking as possible, so I went with tentacle. Gotta represent that Charisma 5, after all! :)