AP weaponry

[Poulp']

AP only takes armour. I'm hard-pressed to understand how it would effect defense skill. As for shield, thats a deflection bonus so AP doesn't effect it. I'm just making the terminology up now.

Foot

well, defense skill isn't taken into account against missiles.

[Moros]

well, defense skill isn't taken into account against missiles.

Try blocking a volley of arrow with a spear or a sword. That ain't easy. A shield however makes it quite a bit more easy. And well armour always helps.
Also an amour piercing attribute having an effect on your enenmies defence skill wlould be a wierd thing.
AP only halves the armour points. Nothing more, nothing less.

[Olaf The Great]

Try blocking a volley of arrow with a spear or a sword. That ain't easy. A shield however makes it quite a bit more easy. And well armour always helps.
Also an amour piercing attribute having an effect on your enenmies defence skill wlould be a wierd thing.
AP only halves the armour points. Nothing more, nothing less.

Unless of course the AP weapon is a inflatable hammer.