This weapon is reinforced with cold iron and set with chunks of obsidian in a foursquare pattern.

An impedance weapon mimics the impeded magic planar trait (DMG 150). When you use it to strike a creature, the target’s ability to cast spells or use spell-like abilities is impeded for 1d6 rounds. To cast an impeded spell or use an impeded spell-like ability, the creature must attempt a Spellcraft check, Intelligence check, or Charisma check (whichever one is made with the highest bonus). The DC for this check is 15 + the spell level. If the check succeeds, the effect functions normally; if the check fails, the effect does not function and the spell or the use of the spell-like ability is lost.

Prerequisites: Craft Magic Arms and Armor, antimagic field.
Cost to Create: 4,000 gp (plus 300 gp for base item), 320 XP, 8 days.