A Librarian can be worth it, but for what he brings to the list at this points level, you may want to look into taking some Land Speeder Typhoons instead.
Now, for the actual list, it really is a matter of what you see your army doing that I have to bring up. Personally, when I run my Ravenwing, I see them as 95% shooting and 5% close combat. The Standard of Devastation really is an effective banner against all forms of infantry, because even against terminators, throw enough dice at something and it will die. That being said, with a 5 man command squad already, I think you could benefit a bit more from having more bikers with bolters to benefit from the banner, and that second squad of knights takes a pretty big chunk out of your list.
The other thing is regarding the Darkshroud Land Speeder. Even though it is cheap, I just don't see the value in this edition. With the short range, you will have to have your army crowded around the Darkshroud to benefit from Stealth in the event your units are shot with something that would force them to jink. Take into account that you will also have your army crowded around the Command Squad with the Standard, and that is a lot of business in a small area. From experience, it is very hard to accomplish.
Just some food for thought, but if you were to drop the second unit of black knights, and relied on the Command squad for counter charge and plasma duty, you can probably add another unit of 6 Bikes, and may have room left over for some Land Speeder Typhoons to give you some long range anti-tank, which this list is sorely lacking.