Backstep, though not a damage dealing skill in Tera, is probably one of the most used skills available to an archer. As the name of the skill implies, the skill allows you to jump back about 5 meters, avoiding attacks, dodging, or just putting more vital distance between you and your foe. Used right, this skill can allow you to get behind a chasing adversary in PVP, to deal rear-attacks, and hopefully knock downs. It does take mana, and has a fairly long cool-down so it is not a skill that can simply be spammed. Binding it someplace with extreme accessibility, such as the center mouse button or other unused mouse button.
Soaring Attack, earned at level(Tera Gold) 14, is a handy knockdown-recovery skill. When in the knocked down state, this skill becomes enabled, and you may quickly do a 360 degree spin attack, which has a high chance to knock down or knock back anything it hits. This takes a fair amount of your small mana pool, but is certainly worth the 2-3 seconds it would take to recover normally. Depending on your weapon and level, it does the damage of around 2 and a half normal shots. This skill is most useful, of course, for PVP.