You can have full parry without foresight...but this is extremely rare...i never saw this happen unless fighting much lower ranked monsters. Comparing parry with evasion, the thing is that steadfast is way stronger than light strike effect. I can easily do 5+ parries in a row with only 82 DEX. Since parry often halves the damage taken, depending of your DEX it can be compared to shield since shield has a nearly 100% block rate but only during active windows.
Also, you can Fracture at partial parries too. I just keep track of mob's "default damage"...if some halved number pops i always give fracture a try ^^ They should add a "Parry" and "Block" messages just like we have miss and evade...would make things much easier to identify.