Re: Mythos of the Werewolf
I would like to recommend that a weapon's being purely of silver or silver-plated should not be an issue. A pure silver blade is not only heavy, but silver is a soft metal and liable to bend if made into a sword. I've worked with the stuff before and it's about as bendy as copper (more-or-less).
I always postulated that if a supernatural explanation was required, something along the lines of "Silver represents purity, and evil can't withstand exposure to purity."
If a more scientific explanation is preferred, "Silver is a known toxin to bacteria. Direct contact with silver leaves behind traces that can sicken the werewolf. Injuring him with a weapon that creates contact with the silver contained therein effectively halts the werewolf's ability to regenerate."*
Or some other way I hadn't thought of. It really depends on what flavor of werewolf you're going for.
*Or perhaps just for that wound?