Grimtools:
Forword:
There are already multiple Cold damage based, dual-wield Reaper’s here, but I think most of them are outdated and / or have some flaws. I think my iteration strikes a good balance between tankieness and damage, leading to a character that can clear all content in the game.
Idea:
Well the idea is simple, get your auto attacks (AA’s) as strong as possible.
Build Concept:
Nightblade and Nercro already provide a lot of damage and leech, leading to a lot of the gear being more tanky oriented instead of going all out in damage. Beronath’s Fury is a must AA replacer and the Weapon Pool Skills (WPS’s) Execution and Necrotic Edge are the main stars of the show.
Ingame stats:
Gear Discussion:
Weapons: Malkadarr + Chillstrife, Malkadar provides the damage while Chillstrife gives up to 10 % Resistance Reduction (RR) if night’s chill is not hard caped. From my playtesting this is the best combination of weapons due to Necro not providing any cold RR and together with the Medal, Necrotic Edge is already a 360 ° AoE nuke.
Rings: Well these are best in slot (BiS) but if you don’t have these yet, you must run Ill Omen for damage reduction (DR). Because The DR only procs of off crits, this build needs high Offensive ability (OA), forcing the pumping of cunning. If your OA is above 3.2k without cunning pumping, feel free to pump spirit. 3.3k OA feels like the sweet spot.
Head: Namadea’s Horns, needs Overseer Prefix for up to 12 % Physical res.
Legs: Reaper’s Legguards are definitely the best here. For my Callagadra kill, I used Deathwhisper for + 6 % Phys res. Feel free to use either of them.
Feet: Wraithwalkers seem better at first glance, but Primordial Rage boots providing up to 105 OA and 528 health making these just better IMO.
Relic: If you feel tanky enough, go Nidalla’s Outbreak or Nemesis, but because Reaper has no innate Circuit breaker I feel like Serenity is required for smooth play.
The Rest I feel is self-explanatory, trying to get as close to 100 % Vit → Cold.
Key Devotions
Murmur: RR
Viper: RR
Rhowan’s Crown: RR
Crab, Hyrian: Flat cold damage and some nice tankiness
Leviathan: Because the Leech of reaper is already high enough and there is no Acid / Lightning → Cold conversion, I feel Leviathan is the best here, providing 18 flat cold and nice tankiness.
Rest aims at getting more tankiness and affinity. If your slow and freeze res is already capped, go with Harpy over Throne.
Play style:
Try keeping Lethal Assault and Soul Harvest up 24/7 and use Ring of Steel for the Fumble. If you feel comfortable, use Mark of Torment to reflect Sunder, else use it for a tankieness boost.
Performance:
Ravager of Flesh in 1 min 1 sec.:
Callagadra in 1 min 47 sec.:
Crate in 1min 17 sec.:
SR 75 - 76 in 5 min 5 sec. (good rooms):
Lokarr and Mogdrogen are of course also doable 
Closing Statement:
Well Reaper is the very definition of a Glass Cannon, thus requiring some defensive help from gear, but it works well, and the character can clear all content. Thanks for reading and have fun with the Build!
. Phoenix devotion is used mostly for Fire builds, but fits here too. My build is squishier, has more RR thanks to Ill Omen, less flat Cold 
, but still comparable damage (in more skillful hands than mine). Because this topic build is pretty sturdy, it can facetank more and deal decent damage at the same time, so results are better. I would try this variant 