I think the silence effect is based on your INT vs. the mob's INT or MND. In exp parties in Caedarva Mire, these would regularly proc on the Spongilla Flies, but never on the imps.
Really Good Arrow for WS, if you cant afford to TP fully in these, then get a stack macro in with your WS, i use these for when Unlimited Shot isnt up, otherwise i'd Unlimited Shot > PPA > WS :D
