Instead of a lengthy post trying to rehash all of the terrific information about Medieval arms and armor, I will humbly redirect all those interested to this article from the Metropolitan Museum of Art. It covers more than just terminology but important details such as usage and history. It even debunks several popular theories about codpieces, blood grooves on a sword, and more.
Very cool stuff for high fantasy writers and MMORPG players.
A big thanks to my buddy Jordan Hinkley, Director of Sword Fight Salt Lake for pointing me to this article. If you have a minute, go check it out.