Yeah.. it pretty much is just vanilla nwn's barb rage, I didn't actually realize that. I just thought it would be cool for blackgaurds to have a sort of drain ability if you will, to further lower other people's stats when the get close enough to them. Perhaps in addition to this, per number of people in the aura suffering the effect, the Blackgaurd could gain an extra bonus to their damage, whatever type it may be. +2 per afflicted enemy in the aura. And mind you once they leave they aura they're no longer stricken by the aura. That was a problem we had with barbarian's terrifying rage aura.. all they had to do was run into and you'd be docked like however many ab it was they decreased per level. 1/4 I think it was.
I remember the way you did it on dex was a lot different but I can't exactly recall what it did, I do know that I wasn't entirely a fan of how blackgaurds worked on dex when Ezruman changed them but at least they were a playable class then.
What would you do with the feat?