Let this end the dispute: a saber is usually but not always curved. From some of the examining I've done, it seems that Cossack sabers were not curved (although that could be the pic quality, the angle is slightly odd). If you go here: http://www.vaulscastle.com/armory.htm, the fourth picture down is a Civil War saber, and the curve is barely noticeable.Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc. wrote: Saber \Sa"ber\, Sabre \Sa"bre\, n. [F. sabre, G. s["a]bel; of uncertain origin; cf. Hung. sz['a]blya, Pol. szabla, Russ. sabla, and L. Gr. zabo`s crooked, curved.] A sword with a broad and heavy blade, thick at the back, and usually more or less curved like a scimiter; a cavalry sword.
Actually, lightsaber does make sense for pure script reasons, particularly when you think about calling it a lighthand-and-a-half-sword . Of course, Luke's style always looked more like longsword to me than saber, with the stances he used.