can you enhance non-armor armor with enhancement bonuses to ac?

[animewatcha]

Aside from the 3 armor categories types, we have things like a Monk's robe, or Shozoku of the Night Wind.

http://www.archivesofnethys.com/MagicWondrousDisplay.aspx?FinalName=Shozoku%20of%2 0the%20Night%20Wind

Can these things be enhanced to give +1 - +5 enhancement bonus to AC?

[JDL]

To keep the answer simple, you can only enchant an item to give armor bonus by RAW if it's a masterwork version of the item. Unless you have a masterwork Peasant's Outfit you plan on enchanting, you're better off using a Wonderous Item that gives an enhancement bonus to armor, such as the ubiquitous Bracers of Armor.

If you mean whether you can improve the armor bonus on a premade item such as the above, that falls under the realm of custom magical item creation, and requires approval by your DM. There are rules for adding abilities, but only guidelines for improvement of existing abilities.

[animewatcha]

The item above gives an armor bonus, but not enhancement bonus. Aren't magic items masterwork by default?

[JDL]

True. By RAW, you can add an enhancement bonus to armor to this item as per the Bracers of Armor bonus provided you meet the prerequisites. Also, since you're adding it to an existing item, it has a 50% increase in cost. To add a +1 enhancement would cost 1,500 gp, +2 would be 6,000 gp etc. Sorry, I interpreted your question being to improve the Armor Bonus.

[animewatcha]

It is. Using the night wind armor, the question is, could I turn it into a +1 shouzoku of the night wind to make it +3 to armor. 2 regular armor ac and one enhancement bonus ac.

[JDL]

Yeah, the confusion is originating from the difference between "Armor Bonus" and "Enhancement Bonus to Armor"

Armor Bonus is the amount of AC an item gives you due to its ability to block attacks. A nonmagical Leather Armor has a +2 Armor Bonus. A nonmagical Full Plate has +8 Armor Bonus.

Enhancement Bonus to Armor is how much extra protection the armor provides from magic. This can range from +1 to +5 and stacks with the Armor Bonus.

The above item provides +2 Armor Bonus. If you wanted to add an Enhancement Bonus to Armor to this, it would fall under the custom item creation rules. I was wrong on the Bracers of Armor, they give an Amor Bonus, not Enhancement Bonus to Armor.