Werespear
These specialized polearms are clearly derived from bear-spears: a Werespear is a six-foot spear with a metal stabbing spear tip and a crossbar, to prevent the quarry from impaling itself further, in exchange for getting within striking range of the spear-holder. However, this is a spear designed for fighting werewolves (and other shapechangers). The wood is reinforced rowan, and is usually smeared with various anti-werewolf herbs and unguents. The crossbar is also much longer, made of silver-coated steel, and features two additional spikes (also silver-coated steel) designed to also pierce the werewolf’s flesh. Finally, the area below the crossbar is likewise covered with silver, just where a werewolves hands might try to grab the spear and leverage it out of the wielder’s hands. Note that the spearhead itself is not made of silver, as silver does not keep an edge well.
Werespears are generally not used to kill shapechangers directly, although the combination of rowan, silver, and razor-sharp steel would certainly be painful and ultimately toxic to most classical werewolves. The general tactic was to use several Werespears to immobilize the werewolf to the point where someone else could shoot it in the head with a silver-tipped crossbow bolt. It can also be used against regular prey like boars or bears, of course; but these weapons are rather costly to use for such mundane purposes. They, after all, incorporate quite a bit of silver in their design.
Treat as a Long Spear (GURPS Basic Set: Characters, page 273), except that the cost will be at 10x base for the campaign. Silver isn’t cheap.
Would this be a good time to note that “were-” literally means “man”?
…No. No, it would not. 😉