on the one hand this sounds good.
on the other I don't know how it would work. poison isn't like enchanting, it lasts a very short time. that may be hard to program on stackable items I don't know. Perhaps if they made it so its applied to the bow instead of the arrows (technical purposes, rp the arrows anyway) it would work, but that leaves out all throwing items.
I dunno though, I'm not a scripty person, best wait for someone who is.