White Nescheres: Dropped from a farmable mob

I was scrolling through all the lvl 100 weapons and I noticed that almost all the weapons are dropped by a semi farmable mob. (eg. ToT mobs, skeles, petris, etc) but the level 100 white nescheres for crafting isn't.

It is possible to have this weapon dropped from lets say a ToT mob so there would be a bit more supply?

I really have trouble farming dual birks when there's only 6-9 mobs mobs in valley of antelope when its shared with regular birks.

Can it be at least dropped from the normal birks as well or a oblivion mob to make it hard?