Don't farm your STR bow at penons, unless you have a REALLY good bow (SoM or more).
On my archer, I was level 52, had maxed fire, lightning and pacheon at 43, and cold at 30. I had a SoS +3 bow. However, the farm was really slow and painstaking.
You are much better off farming at 64. At 64, your skills are at 55, meaning you have book 2 Strong Bow, Anti-Devil Steel and the 4 Arrow combo. It's best to farm at the Power Earth Ghosts.
