I am not sure, but make sure your friend make you a grief zerker and not stupid phase blade.

Ok with zerker, you need atleast 48 ias to max attack frame. So that let you to how much ias zerker grief you need.

I am using bloodfist so I got me a 39% ias zerker, you might need more or less.

also how much foh damage do your V/t does? Mine does about 2.2 k with 5 combat GCs and lvl 87.