I haven't seen this one yet, so what about an edge to resist the con-reducing affect of rot or make it harder to rot someone? Seems like a niche enough thing to make an edge out of.

I think this is a reasonable idea and you'll probably see something like it at some point. At the time we did shaman edges I hadn't yet hit on the idea of "hey, let's release one or more sort of anti-shaman edges at the same time."