Lengthens

A weapon upgrade, weapon modifier or armor piece that "lengthens" the duration of a condition or skill will typically increase the duration by 33%.

Note: This applies not only to conditions inflicted by the weapon that bears the weapon upgrade itself, but also conditions of the same type inflicted by skills. For example: A Necromancer wielding a barbed weapon can lengthen the foes' bleeding caused by the popular Signet of Agony + Plague Sending combo. Likewise, an Elementalist wielding a heavy weapon can lengthen the weakness caused by Enervating Charge.

Tip: To check the exact duration modification, temporarily switch the game language to one of French, Italian, or Spanish. Even if you cannot read the language, the number is there.