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.

Maybe the blindness is a bad idea but it it worked with the knock back it would hinder them, plus it'll be better in pve against oncoming enemies.

It would definitely work in PvE (although methinks decisions 'round here are made more to appease the PvP crowd), and I hadn't considered both abilities proccing- but it's certainly not a bad idea. I just dislike the idea of blinding me since it almost completely negates any skill the enemy may have; most of the time, if I get the upper hand and die it's because I was outperformed or outwitted by my enemy, instead of just being rendered virtually helpless at all but spitting range (barring a really lucky shot). Being blinded by the flashbang either takes some effort in its use and placement, or the victim at least sees the grenade or indicator and knows shit's about to go down (not necessarily knowing he'll be blinded, but at least he's conscious of enemy danger). Seeing a bubble and a guy inside it with helm of saint, you pretty much have to make the decision to willingly blind yourself for a chance at the kill (and tbh, I wish the titan had to be inside the bubble when an enemy enters for the effect to trigger). And I know you haven't shown any sign that you take my comments as anything but constructive criticism, since we've gone back and forth with comments now I just want to make sure I say that I'm only giving an honest critique, and in no way intend it to be offensive. I myself love to come up with ideas like these, and sometimes I get as involved with analyzing someone else's idea as I do my own.