User blog comment:ACWeapons/How much armor would RWBY characters need?/@comment-24891101-20151211164227/@comment-24891101-20151211172835

Para-aramids come to mind first (Kevlar), but you're asking me essentially to develop a bulletproof shirt, which we haven't managed in real life. If we knew how, it'd already exist. Ballistic vests aren't exactly compact, even the lightest ones.