Strike Specific Loot List

At the end of 320+ strikes you can open chests with skeleton keys and get strike specific loot. 
You're guaranteed one skeleton key from your first nightfall per week per account. 
Other than that they are random drops from the strikes.
Chests drop a weapon/armour/class item and/or class item/artifact.

Abdomination Heist - Phogoth
- Mongrel Ogres Grasp's (Hunter Gauntlets)
- Devils Dawn (Sniper)

Blighted Chalice - Malok
- Hood of Malok (Hunter Helmet)

Cerberus VAE III - Valus Ta'arc
- Treads Upon Stars (Scout Rifle)

Dust Palace - Psion Flayers

- Arc Flayer Mantle (Hunter Cloak)
- Solar Flayer Mantle (Hunter Cloak)
- Void Flayer Mantle (Hunter Cloak)

- Treads Upon Stars (Scout Rifle)

Echo Chamber  - Theosyion , The Restorative Mind
- Theosyion Vibrissae Gauntlets (Warlock Gauntlets)
- Imago Loop (Hand Cannon)

Fallen Saber - Saber-2
- Devouring Maw Helmet (Warlock Helmet)
- Baron's Ambition (Heavy Machine Gun)
 
Nexus - Sekrion
- Mark of the Nexus Undone (Titan Mark) 

Sepiks Perfected - Sepiks Perfected

- Devils Dawn (Sniper)
- Sepiks Deposed Bond (Warlock Bond)

Shadow Thief - Taniks Perfected
- Does Not Bow (Auto Rifle)
- Cloak of Taniks (Hunter Cloak)
- Baron's Ambition  (Heavy Machine Gun)

Shield Brothers - Valus Mau'ual + Tlu'urn

- Mau'ual's Maulers (Titan Gauntlets)

- Treads Upon Stars (Scout Rifle)

Sunless Cell - Alak-Hul the darkblade
- Dark Blade Helm (Titan Helmet)
- Dark Blade's Spite (Fusion Rifle)

Undying Mind - Undying mind
- Imago Loop (Hand Cannon)
- Mark of the Undying Mind (Titan Mark)

Will of Crota - Omnigul
- Grasp of Malok (Pulse Rifle)
- Omnigul Bond (Warlock)
 
Wretched Eye - kovik splicer preiest
- Anathema Cannon Mark (Titan Mark)
- Devils Dawn (Sniper)
- Hood of Malok (Hunter Helmet)

 Winter's Run   Nixis or ?
- Stolen Will (Shotgun)

Other Class Items
- Bond of Polarity (Warlock bond)
- Cloak of the Leopard (Hunter Cloak)
- Octopus Cloak (Hunter Cloak)
- Cloak of Trekmor (Hunter Cloak)
- Hood of the Night Sun (Hunter Cloak)
- Mark of the New Sun (Titan Mark)
- Mark of Resolve (Titan Markl)
- Trained Chaos (Warlock Bond)
- Mystic Drain (Warlock Bond)
- The Unconquerable (Warlock Bond)
- Paradox and Truth (Warlock Bond)
- Cloak of Hidden Agendas (Hunter Cloak)
- Cloak of Atropos (Hunter Cloak)
- Rustworn Cloak (Hunter Cloak)
- Mark of the First Pillar (Titan Mark)

If You're looking for a certain slot to raise your light level then you can get better chance of getting an item of that slot by doing the strikes listed below.

primary - cerberus vae  100%
special - winters run 100%
heavy - fallen saber 50%
helmet - malok 100%
arms - abomination heist , shield brothers or restorative mind 50%

class - nexus 100%