Trait is 100% crit when you have fury.
Vengful hammers does not crit with it. Only base crit value.
Impossible odds 2nd strike does not crit with it. Only the 1st hit does.
Is this intended? If so then it is pretty useless.
You're possibly misinterpreting the trait description.
If something is increased by 100%, it is doubled. In order to have 100% crit chance with fury, you would need a base crit chance of 60% from your gear and any food/utility buffs you have.
Basically the trait is +20% Critical Chance while you have Fury.