Talismans have an ability called Poisonous. This causes 2 [CD] damage when you receive a Wound. Maybe Toxic is the same? If your attack causes a Wound, it deals 1 [CD] of additional damage (ignoring armor)? That's the closest thing I could find.
Sounds like a misplaced wording for the persistent quality (which sounds fair for a poisoned weapo,):
Persistent X : The attack has a lingering, deleterious effect. If one or more Effects are rolled, the target will suffer X§ damage at the start of each subsequent turn for a number of rounds equal to the number of Effects rolled. Each effect rolled on the ongoing damage adds one additional round of duration. This condition can be avoided entirely at the time it is inflicted by adding a number of points to Doom equal to the number of Effects rolled; after this, it can only be removed by waiting for the duration to end or by taking the Clear action.