Everything here is subject to change and additions. If you can see a mistake or notice something is missing please say so and it shall be changed. The goal here is to use community collective knowledge to get as close to the truth as possible.
An item is considered Pre-Nerf if it cannot drop anymore. In other words, the possibility of the game generating these stats or items has been physically removed by the coders at Anet, mainly 2005/2006 around the release of Factions. The only way to acquire Pre-Nerf items is through trading with other players.
The following list is items / mods that are observably no longer in the game, not possible because of nerfed foe levels or a known update specifically removed them. It's possible this contains mistakes or is incomplete but it's the best of currently-known knowledge
All Q7 weapons with current max dmg
Q7 Swords above 14-21 dmg
Q7 Axes above 6-25 dmg
Q7 Hammers above 18-32 dmg
Q7 Daggers above 7-15 dmg
Q7 Bows above 14-25 dmg
Q7 Wands above 11-20 dmg
Q7 Staffs above 11-20 dmg
Q8 Staffs with max (11-22) dmg
Q8 Axes with max (6-28) dmg
Q8 Hammers with max (19-35) dmg
Q8 Hammers with (18-35) dmg
Q8 Dagger with max (7-17) dmg
Q8 Bows with max (15-28) dmg
Q8 Bows with (14-28) dmg
Q8 Wands with max (11-22) dmg
All Q8 Zodiac swords
All Q8 Vertebreakers
Q8 OS Shadow blades - Anybody confirmed Shard wolf exception?
All unconditional items
Gold staffs with a requirement of 0
Staffs with a HSR mod in GOLD text
Staffs missing HSR Mod completely (Some exceptions still available from collector/quest rewards)
FACTIONS & Tyrian OS Staffs in restoration req
GOLD OS Crystalline Swords with an inherent mod
GOLD OS Dwarven Axes with an inherent mod
GOLD OS Dwarven Hammers
GOLD OS Krytan Axes
All Swamp Clubs
GOLD OS Serpent Axes in Tyrian Skin
OS Gold/Purple Fire Staffs in "Dead skin" (Other rarities still available from collectors)
OS Gold/Purple Water Staffs in "Dead skin" (Other rarities still available from collectors)
OS staffs with lower dmg than 4-6. Example: q0 2-4, 3-4, 3-5 (Some exceptions still available from collector/quest rewards)
The Henge of Denravi sword, Axe, Bow and Hammer (details to be added)
Blue/purple weapons with dual vamp / zeal mod
Blue/purple weapons with xx/-10 and xx/-5 mod
Items with an inherit mod instead of an inscription or 3 mods. (See Mausoleum / Triple mod research)
All Q8 Gold weapons with a gold value higher than 280g
All Purple inscribable Crystalline Swords
Any Gold/Purple/blue OS Wand with mixed profession mod (HCT / HSR) on a single profession skin. Mixed profession mod on multi-profession skin are NOT prenerf, this include : Amber Wand, Jade Wand, Platinium Wand, Jellyfish Wand, Koi Scepter, Plagueborn Scepter, Celestial Scepter, Wayward Wand, Zodiac Wand.
Any Gold/Purple/blue OS Staff with mixed profession mod (HCT/HSR) on a single profession skin. Mixed profession mod on multi-profession skin are NOT prenerf, this include : Ghostly staff, Shadow staff, Amber Staff, Jade Staff, Bo staff, Celestial Staff, Cockatrice Staff, Dragon Staff, Forbidden Staff, Outcast Staff, Plagueborn Staff, Platinum Staff, Zodiac Staff.
Inherent Gold Weapon mods:
+13%[condition] or lower
+18%[while Hexed] or lower
+18%[below 50%] or lower
Wands with 18% or lower HSR/HCT mod
Wands with +3 Energy
Wands with 8% or lower HSR/HCT
Wands with 13/-1 or lower
FACTIONS Wands with a restoration requirement
Inherent Purple Weapon mods:
+11 or 12%(condition)
+xx%/-5 energy, +xx%/-10 armour or +xx%/-1(energy or health) regen
11-14% While hex.
11-14% while below 50%.
Sundering of 10/9% or lower (Except Sword)
Furious weapon mod 10/4 or lower
Any +25% damage vs Charr
Sword & Axe Vamp with 1-2/ -1
Hammer & Bow Vamp 1-3/-1
Example of some Prenerf weapons:
(If anybody has screenshots of the missing ones please post and I will update.