So you've got access to a blacksmith who can silver weapons.If I were you, I'd get a magic dagger, and see if you can have the blacksmith mount it onto a spear. Failing a magical dagger, take some of those inherently magical monster parts and see if there's some quest or technique to modify them into a magical polearm head. I'd expect at best a magical weapon with no modifiers, and probably some negative effects vs particular opponents, and possibly some debts with unsavory and powerful people. At worst, you may end up with perpetual disadvantage- but that's really only be appropriate if you tie a dagger to a 10 foot pole yourself and call it a spear.

Failing that, as other posters have said, be flexible. You're a fighter. You might be the greatest at polearms, but if it's not hurting them as much as this magical flail, then flail away!