Disarm or Trip using a secondary natural attack

Question

Suppose, there is a Summoner with an Eidolon. The Eidolon has the following natural attacks:

• Bite (primary)
• Claw x2 (primary)
• Tentacle (secondary)

Since the tentacle attack is a secondary attack, it has lower total attack bonus and lower damage, so the Eidolon might be tempted to use it for various combat maneuvers, such as Disarm or Trip.

1. Does he has the same -5 penalty while performing these combat maneuvers as he does when attacking? Where do the rules say so?
2. When disarming, is he considered armed or unarmed (for purposes of –4 penalty on the attack and picking up the item dropped)?

Answer 1

The penalty on secondary/iterative attacks is actually a penalty to your Base Attack Bonus, which is used in the Combat Maneuver Bonus calculation. Decreasing your effective BAB for the maneuver reduces your CMB.

The character is definitely “Armed” (which has a technical definition about threatening attacks of opportunities, which natural weapons can do); I definitely would not apply the −4 penalty. On the other hand, clearly your hand is not full and should be able to grab a weapon. It seems to me that those rules were written without consideration for natural weapons or Improved Unarmed Strike, and the re-use of the term “armed” leads to some ambiguity.

Nonetheless, I think it’s pretty fair to allow no −4 penalty but allow weapon-grabbing.