This is simple, but can really speed up the time it takes to level your Deathknights weapon skill if you're using the target dummies in a major city.
Since you're basically spamming your strikes, and you have a full runic power bar, you can death coil and it's considered melee and will level your weapon skill.
It also works at any distance since it's ranged.
Edit: One other thing to note is that this is a lot more efficient when in [Unholy Presence] which you get at 70. The GCD is 0.5 which is why there is always downtime while you're waiting for your ruins to refresh.