press f6 go to abilities editor and create a new ability based on armor bonus.
-set armor bonus to 0 (if its not a shield
)
-add ur attachments to the right places u know how u said so thats np)
-set number of attachments
-make it an unit or an item spell
-give the ability to a unit if its an unit spell.
-enjoy
if not clear enough tell me and ill post a step by step with names of every thing.