Dual wielding is kinda not so good for single target though.. As you don't have a spammable dps skill besides flying blade.. Well you could go for rapid strikes. Never tried those out as I dont like channeled skills.
And your class stamina morphs are two dot abilities which are kinda not soooo useful. Igneuos shield, dragon leap and volatile armor are useful skills you might want to use. The rest is mostly useless for stamina dk.
Most dks go either 2h for wrecking blow or sword&shield for ransack as spammable dps skills. And 2h is good because of rally, which gives you more healing and a burst heal through reactivating.

And yes medium armor works. More damage and more sustain. Personally I prefer heavy armor, as it provides more defense which I find important considering you have no proper mobility like nb and sorc. But it's individual preference.