Spellpest is an abstract weed (ground up), imbued with innate resistance to magic it is said to be able to somewhat block arcane concentration to the Weave when touched.
----- When applied to a weapon, this fine dust will lower spell resistance of foes struck. With each attack, spellpest will lower the enemies spell resistance by 2 a round, stacking up to 5 times at a maximum of -10 SR.
Charges: 5 Weight: 0.3
Special Properties: Use: Intelligent Weapon 1 Charge/Use (dont know what it'd be called )
Stacking, on top of others. If it can only be consumed/used in Limbo,EE etc.. surely it would be ok? And make tanks having it more of a requirement.
As for the duration, i dont know .. maybe like 2 turns or something. Since it's only got 5 charges and you would need to find more to be able to consistently use them. Maybe a set drop from a boss, always drops 1 or 2?
Hmm, maybe... then in that case. Instead make it -3 sr on hit as a 1 time drop (stacks with NB, Mord, BC) and make it a permabound item. -3 Isn't too high, nor is it useless, a nice little add for tanks to be slightly more useful.