Keen Elven Curved Blade Multiwielded One-handed Question

[Resha]

So I'm enamoured by the idea of a Kali or Gilgamesh style eidolon and I wanted to try to maximize crit capabilities (and magical effects). I want to see how feasible it is, but with all the different rules I'm bringing into the mix, I'm a little lost in the RAW/RAI of exactly what my penalties are. Just want to bounce numbers off people and see if my math is right?

Non-proficient(-4/-4), multiweapon non-light weapon off-hand (-6/-10), two-handed in one hand:
-Impossible
Feat Lighten Weapon (two-handed in one now possible @ -2/-2:
-12primary/-16off-hands
Feat Exotic Weapon Proficiency(Elven Curved Blade) -4 proficient:
-8primary/-12off-hands
Feat Multi-weapon fighting -2 primary/-6off-hands:
-6primary/-6off-hands
Feat Improved Lighten Weapon remove -2/-2:
-4primary/-4off-hands.

This would be eidolon at level 9, evo 6 pairs of arms, giving me 12 Keen attacks for 1d10+1 15-20x2 crit, plus possible thundering/bursting effects.

So 3 questions:
1) Are my numbers right?
2) Is this the best I can get? Are there any ways to get the negatives down even further? (I am aware of many different ways to increase the eidolon's Str/Dex score. What I'm asking for is some other rule/feat/game mechanic I may be missing)
3) Is this a viable build or should I just resign myself to a measly 6 attacks?

(and yes I had just considered having it just throw alchemist's fires for 12d6/round)
Thanks in advance for your feedback!

[Bronnwynn]

Lighten Weapon is third party, mate.

Also, six attacks is not measly.

[W. John Hare]

And you can't take the Improved Lighten Weapon at lvl 9, your Eidolon only has a +7 BAB at that point.

[Lifat]

So, your numbers are correct, but you are using third party rules and there are no other ways to lessen the penalties (standard at least, there might be other third party).
Also, 6 attacks at lvl 9 is very strong, especially when you can haste it on top and have such a high crit chance with a relatively high damage weapon.

[Nefreet]

This should probably get moved to the 3rd Party Forum (though with the holiday it might take a while).

[Lifat]

Nefreet wrote:

This should probably get moved to the 3rd Party Forum (though with the holiday it might take a while).

That depends on whether or not the OP intended to use 3rd party stuff and want 3rd party suggestions.

[graystone]

Lifat wrote:

Nefreet wrote:

This should probably get moved to the 3rd Party Forum (though with the holiday it might take a while).

That depends on whether or not the OP intended to use 3rd party stuff and want 3rd party suggestions.

To answer his questions requires the use of 3rd party materials. I'd say that requires a move to 3rd party...

[Malachi Silverclaw]

It requires a third party feat (or two), as well as EWP(Elven curve blade), another feat.

This can all be avoided by using an 18-20 light martial weapon, like a kukri. Think how many feats you'd save and be able to spend on other things! Think of the penalty only being -2! All this, just by accepting 1d4 damage instead of 1d10. Use the extra feats to get more flat bonuses to damage, and your lessened attack penalty will mean your DPR will probably be the same anyway!

[graystone]

Make your eidolon a quadruped, take the Natural Jouster and multiweapon feats then charge with 6 lances.

[Black Powder Chocobo]

Alternative would be Sawtooth Sabers as with the Exotic Weapon Prof there they count as light for two-weapon fighting. 1d8 damage base with 19-20 crit ain't that bad.

[Dafydd]

you can skip the proficiency feat by droping a set of arms or 2 and using a kukri. (using the 4 evo points for weapon proficiency)

that would give you 8 attacks, each at -2.

Additional option, drop down to 6 arms total, taking claws. Add a sting (to give it battle field control with increase threaten area). You will save a TON on weapons (64k for a Keen Thundering ___ Burst vs 300k for 6 +1 Keen Thundering ___ Burst ECB or 400k for the 8 kukris)

Course, that limits you to 7 total attacks, at level 20.

[Resha]

Thank you all! Great suggestions! Although a few ideas were quite interesting (Lance Jouster/ cheaper natural attacker) they don't really go with the theme I was aiming for (but yes, I'm aware of the cost ;p). As much as I like the idea of -2 vs -4 kukri just don't look as sexy in my mind, though I would probably still go that route vs sawtooth sabers just for the extra crit range.
Thanks again for all your input!