there is a structure that allows you to sell armor for food. so i have a dwarf with armor of 8 and i cash it in for 8 food, then is he still considered "armed". there is another structure that says "get X bonus points if *none* of your dwarves is armed"...would my "0 power" dwarf qualify?
It is "Peaceful cave" that lets you sell armor for food:
At any time, you can trade the Weapons of your Dwarfs for Food. You get a number of Food equal to the strength of the Weapon you trade in.
It is "Prayer chamber" that gives you Bonus points if none of your Dwarfs are armed:
When scoring, the Prayer chamber will be worth 8 Bonus points if none of your Dwarfs that are in play have a Weapon. (You can use the Peaceful cave to trade the Weapons of your Dwarfs for Food. This way, you can get rid of the Weapons of all of your Dwarfs and get the 8 Bonus points for the Prayer chamber if you own that one as well.)
As you can see, the Appendix anticipates exactly the usage about which you asked.
Your "0 power" Dwarf would indeed qualify - but to get the points from Prayer chamber, you would have to ensure that each of your Dwarfs has 0 power (either because you never armed it, or because you disarmed it with Peaceful cave).