When wielding a reach weapon can you use armored spikes to make Attacks of Opportunity?

Question

Something showed up in Harry Potter and the Natural 20 (a HP & D&D 3.5e fanfiction) and I was wondering about application in pathfinder: When wielding a two handed reach weapon (or 1 handed with shield), can you can use armored spikes to make Attacks of Opportunities against foes nearby?

The Reach quality for weapons only specifies that you "can't use it against an adjacent foe." And the Spiked Armor quality specifies that you can use it as part of a grapple, or as a separate attack.

Edit: Just finished that page of the HP fanfic, and it mentions a note at the end that the above technique doesn't work in pathfinder according to an FAQ. However, that's after the entire D&D tip section, so it could be referring specifically to using a two handed weapon and TWF abilities to wield the armor spike as an offhand weapon. Bonus: does anyone know what FAQ is being referred to?

Answer 1

Yes, you can

You are wielding a weapon that threatens adjacent squares, and using both hands on your polearm does not interfere with the use of the armor spikes. Thus, you can make attacks with them and threaten the squares they reach.

Note that there is usually a hefty gold cost to doing this, as you have to pay for two weapons instead of one. Typically a reach-weapon-user’s armor spikes lag quite a bit behind his main polearm in terms of special abilities.