7.2 Arms thingys!
Q: What traits should I get first?
A: Go for the new golden trait, after that whichever trait sims the best for you. The value of ETW, PS, DB and CB vary to much between different chars that it's impossible for me to give a definitive answer that fits all.
Q: Arms or Fury in 7.2?
A: Same answer as in 7.1.5, whichever you want, they're both real good!
Q: What relics should I use?
A: Same as in 7.1.5
Q: Should I use BS on single target now?
A: Bladestorm is not worht using more than it is in 7.1.5. We need T20 for Bladestorm to be worth using as a single target nuke. (Note that it's really damn good with the new trait on AoE tho)
Q: Should we still look to use a Crafter neck?
A: Yes, if you can get your hands on a Savant (Pure Mastery), it's going to remain BiS almost forever, if you don't have a Savant, high itemlevel necks with good stats may edge out. Also depends on how efficiently you can utilize Heroic Charge on any given fight, obviously. (Note that Crated Gear goes up to 875 with 7.2)
Q: How will T20 / new raid trinkets change things?
A: Raid is still a while away, I'll look into those things when it becomes more relevant.
Q: What Legendarys should we use?
A: Long answer; The value of our Legendarys as Arms vary greatly depending on what gear you have, and what relics you are using. Also obviously depends on what piece of gear you're replacing.
Short answer; Note, used a generic NH Heroic geared Profile, with a crafted Savant neck. The results on this picture may or may not represent what you'll see if you sim it out yourself for your own char. http://imgur.com/a/Ov79u
Just some quick things for 7.2 to get you started!