...the backing can be. which i said.
my understanding is that a longsword is a one-and-a-half or two handed sword that can be used as a sidearm, a greatsword is a sword that is long enough to be classifiable as a polearm, a bastard sword originally meant a sword whose maker was unknown but now often refers to one-and-a-half hilted swords, and arming swords are one-handed doubled edged swords that eventually split into broadswords and longswords, but that each category is also sort of malleable because history is weird