Unless they've fixed it, Archery damage is based on STR instead of DEX. See the thread entitled
Archery uses STR instead of DEX!!!!
Everyone is saying Dex governs archery damage, because it's supposed to, and the Wiki says it does, and Brad McQuaid said it does. But it doesn't currently on P99. This may be an EQEmu code mistake.
The upside is that rangers can gear for Str to increase both their melee and archery damage.