A bastard sword - by ©MathKnight
A bastard sword, or hand-and-a-halfer, are swords which fall between the longsword or broadsword and the two-handed greatsword in size.
Size
The bastard sword is mostly distinguished from a longsword because it has a grip long enough to allow two-handed use. Bastard swords have slightly longer blades as well, but they remain light enough to be wielded one-handed should the need arise, unlike the greatsword that requires two hands.