Do Armor Spikes add +1d6 to damage while grappling (which is what the description seems to say), or does the 1d6 piercing damage replace normal grappling damage?
So If you were to use a dagger to attack someone in a grapple you would do 1d4+strength, +1d6. The part I am not sure about is if you add your strength again because of the way it refers to the weapon table, but its probably just an extra +1d6.
Moon-Lancer has the right quote but the wrong conclusion. Armor Spikes will add additional damage to damage done with a grapple check, but not when attacking with a light weapon in a grapple.
(Course, now's the time when Hypersmurf pops up and says we've both got it wrong...)