Spellpiercer

+1 to damage and to hit Damage from the sword ignores resistances to nonmagical attacks.
Deals double Damage Dice to Shades
While wielding the sword you can use a bonus action to stick it into an active magical effect such as a spell.  Roll an arcana check DC 10+spell level if you succeed you cancel the spell.

History

Having Spent the last 30 years in a magical prison Ribhus decided to use the chance of forging a Rimstone- or rather a much rarer Rimmetal sword, to create a real disruptor. While lacking the forgegems to empower it to its pinnacle, he was able to create a tool that would not only be able to withstand magic- typical for the material chosen. But also actively disrupt spells, especcially weaker spells.

Item type

Weapon, Melee