Wyvern poison stains, throughout your career as a smyth/ armourer you may encounter wyvern poison staining upon metals. Most commonly from would be wyvern tamers. ( be sure to collect payment upfront for such individuals as they usually expire before debts are settled) 

Unlike acid stains Wyvern Poisons-

• Do not degrade the metal

• Leave pink/purple streaking

• Impossible to remove without UNIVERSAL SOLVENT

Additional notes,

• Some collectors may desire this effect

Armourer and smyths shop guide. 5th edition, Pg.12