Double strike

From GuildWiki

Double strikes are a unique characteristic of daggers. A double strike hits the target twice in one attack. The damage and chance to hit for each strike is calculated separately. Dual Attacks that successfully hit always result in double strikes; therefore any additional damage and effects the skill applies will trigger twice.

With 0 Dagger Mastery, your chance of executing a double strike with daggers is 2%. Each additional rank in Dagger Mastery will increase your chance to double strike by 2%. Some skills like Locust's Fury can alter the chance of double striking. With 12 in Dagger Mastery you have a 26% chance to Double strike.

To simplify calculation, each rank in Dagger Mastery effectively results in a 1% faster attack rate (with 1% starting at 0 Dagger Mastery). For example, 14 Dagger Mastery would result in an attack every 1.13 seconds (because 1.33*[100-(14+1)/100]=1.1305).