In lore the sith made their blades alchemicaly... well at least treated them alchemicly so they could go toe to toe with a lightsaber wielding jedi. I would certainly say it could, as to being able to wield it not so sure. Possibly due to it being a well made blade that has been treated and made more deadly, but it could also be exotic as i would imagine each blade was made in a peculiar fashion and the weight sits funny or the sith that made it crafted it for his own hand and not that of another. Up to you in the end. As for the PC's using it depending on if anybody can identify it as a sith blade and not some really flashy sword i would imagine it is okay until a historian, jedi, sith or other applicable individual comes around and see's the blade then it gets interesting "Why sir i see you have an ancient dark side weapon..." probably not that obvious but something along those lines yes?