A relic from the Great Plague, the Mire Infested sword is a brutal weapon. It not only cuts into the enemy but it infects the wounds of it's victim with a toxic nerve poison. Deals toxin damage on ground slam and charge attack.
The additional Toxin damage is not listed in the Codex, but can be seen in the Arsenal UI.
The in-game description of the Mire states that it applies Toxin damage on charge attack and ground slams but this is misleading. Only ground slam attacks deal pure Toxin damage, as the description states. All other melee attacks are mostly Slash damage with additional elemental Toxin damage. This extra damage is 10% of your damage.
Charge damage was removed as a mechanic (except from thrown melee weapons) as of Update 13.
The Toxin Damage is first elemental applied unlike other weapons that deal innate elemental damage. This makes it nearly impossible to not apply any elemental damage types that do not use toxin as a base. Refer to the page Combined Elemental Damage for more information.
Prior to Update 11.1.0, there was a bug that caused the Mire not to deal Toxin Damage on its own. Update 11.1.0 corrected this bug.