As the titan is the only class I just don't feel right playing in crucible, I'm probably more critical of it. But the blind ability on melee attacks means you've just blinded someone who knows you pretty much have to be right next to him. Unless you got the drop on him, he's most likely going to mash his own melee button, and, 9 times out of 10, will likely hit you anyway. It might not kill you, but in a lot of circumstances the blindness won't hinder them as much as you probably intended with the idea. If this does happen though, my suggestion after melees that potentially blind would be to jump straight up.