Death Knight Help


I am now trying to develop a Death Knight, playing at Veteran difficulty.
This is my current character, based mainly on vitality, Aether, and physical damage, and I would like to try and keep the sword and shield style.

With him I can pretty much destroy everything I encounter with little or no difficulty (albeit a bit of time due to low damage output). It’s just level 30, I know, and it’s just veteran, but it seems to work.
However, I am sure it could work way much better with your help, especially because I have not the faintest idea about how to spend points in devotions, so I really ask for your help, becuase I like both this toon and the idea around which I built it.

Thank you very much in advance