Comes from the online slang: "to nerf" (--> weaken a specific item, because it is or has values that led to an unbalance and had to be reduced).
Unnerfed is the opposite which means that the item is not weakened.
Example:

Soul Sword v.1.03 100 Damage
Soul Sword v.1.04 90 Damage
This item is unnerfed.

They need to nerfe this gun, it is too over powered.
by BainDmG April 13, 2016
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