You're right, I missed the possibility for a -10% resist roll. Although, I still think that it would be nice to be able to farm for something like that outside of the Crucible. There are those of us who prefer the solo life:) Wishful thinking I suppose:)
Unfortunately, feral attack speed doesnt work the way it is supposed to. If it did, this item would be absolutely busted on a shifter. But its base stats are good enough that if you wanted to, you could just socket it with shaels and use ias enchants and have dps comparable to or higher than a physical zealot or frenzier. I forget what my exact calculations on it were.
Game, could you tell us what weapon it represents? like thunderfurry was phase blade or berserker axe (I dont remember exactly) . Would like to know ias frames of this weapon.