I kinda did it by accident. The last word was the last exotic hand cannon I got in year one, never used it much because I always preferred hawk moon. Finally decided to give last word an honest try at learning it. Put it on my warlock and made myself use it when ever I was on my warlock in pvp. Not even thinking about the quest at all. One day it popped up that the quest step was completed. I honestly have no idea how many matches it took. I never paid attention to my progress.