11:55:17 AM Dec 23rd 2014
One thing that should be kept in mind when discussing this trope as far as medieval/ancient/fantasy combat goes is the difference between flimsy cardboard style armor getting casually cleaved through by any strike, and armor being bypassed by proper technique utilizing precise strikes to unprotected gaps in armor. The latter doesn't imply uselessness in quite the same way as the former does.
03:28:30 PM Nov 15th 2011
Yu Yu Hakusho Abridged presents us with "The law of male shounen heroes," which suggests that whenever one takes off their shirt, they become powerful to the point of being unbeatable. This might be the furthest extension of this trope, where even the flimsiest of armors, clothes, keep people down, and could be coupled with the Chainmail Bikini concept.