Wyrdskin is a Unique Gloves in Diablo IV Season 15 for All classes. It comes from General Unique Pool - every Lair Boss (Initiate, Greater, Exalted, Belial) can drop it in addition to their dedicated table (one guide's Boss Loot Table Cheat Sheet).
Unique power
Attacks apply Vulnerable to Distant Enemies, and Weakened to Close Enemies. You deal [30 - 40]%[x] increased damage to Enemies that are both Vulnerable and Weakened.
Affixes
Primary Core Stat
Vulnerable Damage Multiplier
Where it drops
General Unique Pool - every Lair Boss (Initiate, Greater, Exalted, Belial) can drop it in addition to their dedicated table (one guide's Boss Loot Table Cheat Sheet)