Advanced Dark Sight

I maxed it and sort of regret it now. It's pretty annoying having a ds+foh marco that leaves you still in ds ruining your attack sequence.

Please someone tell me one of its uses, or a reason why you find it useful.

I don't see why you're complaining.
Back then you couldn't pot during dark sight and being 1/1'd during advance dark sight was a pain in the ass.

I maxed it and sort of regret it now. It's pretty annoying having a ds+foh marco that leaves you still in ds ruining your attack sequence.

Please someone tell me one of its uses, or a reason why you find it useful.

It skips CoH's delay. So if you use CoH and Advanced Dark Sight activates (about 24% chance since grabbing also count as an attack), you can use another CoH right away. This provides slightly higher DPS and longer invincibility frame.

However, from what I have experienced, I find spamming Upper Stab (in macro) does the best single target DPS for Dual Blade and I'm not the only person who feel this way. I can add more details on this but this is not the right topic.