This topic comes up enough that I think it is worth continuing it here.
After seeing a post on Tank Spot that Dancing Rune Weapon provided threat, I tested it and found that it does indeed provide threat. I used Omen to do the testing since it provides the actual threat you have on a unit in the game. It isn't a calculated or estimated amount by an add-on. It uses the WoW API to retrieve the true threat value.
When you activate DRW, you will get threat equal to the damage it does. It does not get the threat multiplier for frost presence. Therefore, the total threat is only the damage it does. Since the DRW does 50% of your damage for 12 seconds, it should provide a boost of approximately 25% threat for 12 seconds every 1.5 minutes.
One of the interesting things I found out while testing it is that DRW auto-attacks on its own. It is not using your auto-attacks for its damage. If you cast DRW on a mob at range or run away after casting it, it will continue to attack the mob and do damage and provide you threat. This may have some interesting and fun applications.
Salted from DKi also created a video showing this effect. He established some threat on a mob and a druid then taunted it off him and then stopped attacking. When he cast DRW on the mob, it then switched back to him. Further proof that DRW provides threat.
Here is his video:
This testing was done on 3.3.2 and it still is true on the PTR so it should remain in 3.3.3.




