Here's a link to an archive of spell data files.
Epics were released with the Sep. 19, 2000 patch.
Rage of Vallon effect on 9-20-2000
The next available spdat in the archive shows the same effect as on p99 currently.
Rage of Vallon effect on 11-16-2000
"Lowers you on the target's hate list by" is poorly worded in the EqCaster program. The modifier is +500. Concussion's effect is listed as -400 for comparison.