Does taking the unpredictable edge help against skills that stop fleeing like cutoff or parting block?

It's for striking legacy and martial trance.

Against anything else it doesn't have a noticeable effect.

At least, that's how I've felt having played with the edge for around 1000 hours.

How does it helps against martial trance? Did you play a warrior? Woould it help, say, a conjurer?

You don't have to worry much about martial trance stopping you from fleeing.

It may also reduce the offense boost of martial trance but I can't be sure and don't think it does.

I've had it on numerous classes.

In particular it was one of my most useful edges on Tsalantha the ap. Because having a flee blocked can easily be lethal if your tanking is poor.

Would I get it on a conjurer? Possibly, but conjurers have a lot of other useful edges, so probably not.