Breastforce like Breastplate.

Breastplate - Wikipedia

Of course, since all the Breastforce's "Breaster" partners (which could each form a breastplate, be a drone, and turn into a handheld weapon) were beast-shaped, some people call the Breastforce the "Beastforce."

 

That might make sense, except that armor doesn't always have to cover the entire body. Greaves only cover the feet and shines, a spaulder only covers a shoulder, and a helmet may be exclusively for the head. They're collectively pieces of armor, albeit small ones, and it is not always cost effective to have a whole set, yet they are still considered armor. A shield is a mobile barrier that can be used to defend any part, or even the whole, of the body.

I know, I'm being nitpicky, but it's like saying Prime Laserbeak is a shield just because he forms a part of Soundwave's armor.