Or namely, the summoner is.
At level 10 the Summoners Eidolon, if min-maxed, can make 18 attacks with a full attack. With a strength of 30. This is before any magic items or spells of any kind.
And I think my DM is going to throw one at us to try and kill us all.

Anyway, it works like this:
Feats: 4
Power attack, multiweapon fighting, Improved unarmed strike -or- exotic weapon proficiency sawtooth sabre, (a long sword that counts as light for off hand) & double slice.
unarmed strikes are better, it is much cheaper to buy 1 amulet of mighty fists and have it apply to all punches AND natural attacks than it is to buy and enchant 12+ swords. But it might be a bit iffy on whether or not you can make punches with the arms. Nothing says you can't, but nothing says you can either.
Base form: Biped (2 arms, 2 legs & 2 claws)
Evolutions: 18 (14 base +2 feat +2 half-elf)
Large 4 points
Limbs (arms) 2 points
Limbs (arms) 2 points
Limbs (arms) 2 points
Limbs (arms) 2 points (Yes I'm fucking serious)
Limbs (arms) 2 points
Limbs (arms) 2 points
Bite 1 point
2 claws 1 point
There is no limit anywhere of how many times you can take the arms evolution.There is a hard limit of how many natural attacks you can have, but that specifically applies only to natural attacks.
Now for strength: 16 base +4 given str bonus +2 level ups +8 large = 30
+4 for bulls str or item =34
+2 enlarge person =36
Standard buffs at this level: mage armor, shield, barkskin, haste, enlarge person & greater invisibility. Probably not all of them, but at least haste.
TL:DR
If buffed with at least haste (and I got my math right) the Eidolon will get 18 attacks, at +17 to-hit (and one at +12 to-hit) and all for at-least 1d4+14 damage. and that is with just a +4 str item.
And that is just the summon, the summoner is a decent caster by itself. Fucking. Broken.