I’m struggling with DPS on my DK outside of her CD window, so I was curious about which weapon to prefer, before the patch comes live. Yes, I’m aware that DW is almost mandatory for razorice builds, but mine is more of a generic question. Which weapon do you prefer?
I always played Unholy so maybe my stats are not very frost-efficient, but it seems I am one of the few DKs who noticed a drop in dps.
If you use 2 handed frost, you need 30% critical strike rating and 20% haste, then rest in to mastery and critical strike. 2 handed frost starts to pul ahead of duel wield at around 30% critical strike, and 2 handed frost also likes haste more than duel wield.
2 hand is currently simming a little bit higher than duel wield.
Well, 2H tuned higher with the right gear with most build. Thus, it has become the ‘go to’ option for most of guide and top community players. Imo, you can play very fun gameplay loop DW with Shattering Blade and FB, especially in Dungeons. This build is DW only because you have to use main weapon with razorice and off hand with FC. Personally as i said before in other topic, you can drop The Long Winter and Icy Death Torrent for Hyperpyrexia and BoS and i do believe you will have very strong ST/PRIO damage as well. Maybe even stronger then 2H build when having 4 tier set pieces. Then Riders of the Apocalypse will serve you well because you will have nice uptime with Fist of Souls which is 20% buff to FS, FB and BoS. But outside of the Shattering Blade - FS focus builds, 2H has the upper hand this season.
I have felt the same issue. My DPS is great for about 8 sec, and then I gotta wait at least 30 sec before it feels great again. 
I’m loving the rework gameplay wise, but the sustained damage on Frost is incredibly low.
And survivability feels half as good as Unholy.
I tried running 5 Delves as Frost, but in the end I was just left feeling frustrated.
Unholy feels amazing though, and I love the rework it got A LOT. 
Especially because it feels 95% ranged, with only Unholy Assault and Apocalypse requiring melee distance. Everything else is ranged.
Unholy kind of feels like playing a mix between SV Hunter, but with Affliction Locks disease mechanics hehe.