Stacking question

[anest1s]

Chainmail +1 has a +1 enhancement bonus, making its Armor bonus +6. A Heavy Steel Shield +1 has a +1 enhancement bonus, making its Shield bonus +3. I am absolutely certain that you've stacked bonuses in this way before.

Magic Vestment works in the same way as permanent enchantment (and overlaps with it).

I sure have, but I sure as hell haven't realized that before
I would give you exp for explaining it, but it wont let me

 

[Vespucci]

Barkskin is a Natural Armor bonus, which is distinct from Enhancement or Armor bonuses.

And a shield is one specific exception to the stacking rules, in that it grants an Armor bonus that stacks with Armor (but not with the Armor bonus from Bracers of Armor). Looking to that as proof of stacking rules is weak on the face of it.

There are other bonuses that can be added to armor or shields, such as Luck, Divine or Profane that would stack with both Armor and/or Enhancement bonuses. Simply because something adds to a suit of armor's total value doesn't make it an Armor bonus.

Note: As I said in my first post, my own gut-level reaction would be to say no, they don't stack, but the letter of the rules seems to suggest otherwise.

As far as Magic Vestment being cast on both armor and shield... I wouldn't allow the spell to stack with itself. No matter how we try to twist it, that one is explicitly forbidden.

Oh dear. Let's go through this point by point.

1. Barkskin provides an enhancement bonus to the creature's natural armor bonus. That's straight from the spell description.
2. Shields grant a shield bonus, not an armor bonus. These are distinct types, not an exception to the general rule. (Our friend the Shield spell also grants a shield bonus to AC.)
3. The letter of the rules backs up your gut. Magic Vestment provides an enhancement bonus to a suit of armor's armor bonus. It has a specific exception allowing a suit of clothes to be affected as if it was armor. Bracers of Armor provide an armor bonus. This does not stack with armor bonuses from any other source, including clothes affected by Magic Vestment.
4. The enhancement bonus from Magic Vestment does not stack with any other enhancement bonus. If an 8th-level cleric casts the spell on chainmail +1, the suit's armor bonus goes from 6 (5 base +1 enhancement bonus) to 7 (5 base + 2 enhancement bonus). The cleric can't use further castings of Magic Vestment to further improve the enhancement bonus to the chainmail's armor bonus. She can cast Magic Vestment on a shield being used by the character wearing the chainmail, giving that shield a +2 enhancement bonus to its shield bonus.

 

[Patryn of Elvenshae]

Am I seeing it wrong?

Yes.

Enhancement bonuses improve whatever it is they're applied to.

Thus, your leather armor +2 grants you a +4 armor bonus to AC, not a +2 armor bonus and a +2 enhancement bonus. The enhancement bonus is applied to the armor's existing bonus, and you get the total.

 

[Arkhandus]

No, they do not stack.

Magic Vestment grants an enhancement bonus to the item's armor bonus. Ergo the affected robes gain an armor bonus as a result. Bracers of Armor grant an armor bonus, and two armor bonuses do not stack.