How to get higher dmg?

Hey, i wanna say sorry for my english, i hope is understandable, so i just started playing in Tera 7 days ago, today i reached lvl 69 as a Reaper, i got Dark Light staff and i though is enough to get good dmg to kill enemy quicker from quest at lvl 68 but they still taking like 5 mins to kill one of them, same with dungeons, for me taking down small group of enemy is taking long time, when ppl with lower lvl getting them almost instantly, what do i have do to get this dmg? i heard to put crystal to weapon but the spots are blocked.