You would have to use a lot of varnishes to make it a regular weapon in Perf and PVM in general. That, of course, is the problem. They are fairly common, and they are the extreme end of the balance spectrum. I still see mages casting premo as they stand around these days, as if it would even matter when I have the varnishes on hand to end them in seconds. It makes high level DR spells a non factor. Even at +3 varnishes would cut through nearly every form of DR, including that of greater undead, and +4 is basically for the AB boost. +5 is just overboard, and entirely too common to boot.