Okay, let's delve into this conversation a bit.
I have an experience playing multiple classes here on l2Destiny over the course of past years and quite honestly never felt like Soulhounds needed much of a nerf.
My only suggestion (if needed be) would be to address just "Steal Divinity" and make it work similar to other well established PVP servers by:
Removes buffs, however, only for 15 seconds duration.
Or decrease the amount of buffs removed by 1 or 2.
Damage wise, Soulhounds are quite fun to play with, but that is only until people stack enough Unholy damage resistance/armor attribute.
As stated above, in my experience playing soulhound you're not really suit well for endgame PVPs anywhere.
While this class stands out on its own in Olympiad, you don't really want to nerf it every time someone complains here on forum.
Don't make a precedense just because of a few people's outcry .. you're only setting yourself up for disappointment.