the thing with Dark Eldar is that once you point a gun in their general direction, something dies. Their strengths are the RIDICULOUS amount of Dark Lances they can field (or Disintegrators, if they feel like swapping out, but the lists i typically see field mostly DLs, with only one or maybe two Ravagers with Dissies). I know that i personally can fit upwards of 20 DLs into 2k points, half of which are mounted on platforms that move 12" and can still fire them.
Against DE you simply have to dump more fire into them then they can dump into you. DL spam lists are attrition lists, they work to disable your army before you can disable theirs. As others have said, lots of shots are your best bet. S4 AP anything is good enough really. The majority of their armor saves will be 5+ or worse, so just take weapons that will dump out a lot of shots. Identify his firing lanes and try to neutralize them with Heavy Bolters, Assault Cannons, and the like.
And Yes, Open topped weapons are Vulnerable to blasts.
Against DE you simply have to dump more fire into them then they can dump into you. DL spam lists are attrition lists, they work to disable your army before you can disable theirs. As others have said, lots of shots are your best bet. S4 AP anything is good enough really. The majority of their armor saves will be 5+ or worse, so just take weapons that will dump out a lot of shots. Identify his firing lanes and try to neutralize them with Heavy Bolters, Assault Cannons, and the like.
And Yes, Open topped weapons are Vulnerable to blasts.
