I found this while pvping yesterday evening, since I didn't find it with a SEARCH I will share this.
It isn't any exploit, more like a tip for all archers.
If you're playing archer, get your bow and shoot your enemies from BACK
Your damage will be increased by 100-200.
My probes:
First probe: PVP vs. Tank - 1034 dmg from front, 1178 from back.
Second probe: PVP vs. Archer - 1324 dmg from front, 1422 from back.
Third probe: PVP vs Mage - 1523 dmg from front, 1672 from back.
Tip's useful situations:
When your stun shot landed in pvp, run behind the opponent and shoot him down.
When someone flagged, run behind him and start shooting.
Tested on L2G-Oldskool (C4 OFF)
Regards, Lain.