Splinter Spell Resistance

Transmutation
Level: Artificer * 2, Bloodrager * 2, Magus * 2, Shaman * 2, Sorcerer */Wizard * 2, Warlock * 2
Components: V, S
Casting Time: 1 Standard Action
Range: touch
Target: melee or thrown weapon or up to 50 pieces of ammunition touched
Duration: 1 minute/level
Saving Throw: Fortitude negates
Spell Resistance: no
  You create an aura around the target weapon that weakens a foe's magical defenses. The first time each round the weapon damages a creature with spell resistance, that creature's spell resistance is reduced by 5 for 1 round. This reduction is not cumulative for multiple attacks within the same round, even if the target is struck by different weapons, each affected by a different casting of splinter spell resistance. However, the same creature's spell resistance can be reduced on multiple rounds by subsequent hits.